updated Random() to SecureRandom() (#1670)

* updated Random() to SecureRandom()

* batch 2 of SecureRandom updates

.all-contributorsrc

@@ -1404,6 +1404,15 @@
       "contributions": [
         "translation"
       ]
+    },
+    {
+      "login": "richardmr36",
+      "name": "Martel Richard",
+      "avatar_url": "https://avatars.githubusercontent.com/u/19147333?v=4",
+      "profile": "https://github.com/richardmr36",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 4,

.circleci/config.yml

@@ -1,9 +1,52 @@
-version: 2.1
+#
+# The MIT License
+# Copyright © 2014-2021 Ilkka Seppälä
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
 
-orbs:
-  maven: circleci/maven@1.1
+version: 2
+
+jobs:
+  sonar-pr:
+    docker:
+      - image: circleci/openjdk:11-node
+    steps:
+    - checkout
+    - restore_cache:
+        key: jdp-sonar-pr-{{ checksum "pom.xml" }}
+    - run: |
+        if [ -n "${CIRCLE_PR_NUMBER}" ]; then
+          MAVEN_OPTS="-Xmx3000m" xvfb-run ./mvnw -B clean verify org.sonarsource.scanner.maven:sonar-maven-plugin:sonar \
+             -Dsonar.pullrequest.key=${CIRCLE_PR_NUMBER} \
+             -Dsonar.pullrequest.branch=${CIRCLE_BRANCH} \
+             -Dsonar.pullrequest.base=master
+        else
+          echo "No Sonar PR analysis as this is not a pull request"
+        fi
+    - save_cache:
+        key: jdp-sonar-pr-{{ checksum "pom.xml" }}
+        paths:
+        - ~/.m2
 
 workflows:
-  maven_test:
+  version: 2
+  all:
     jobs:
-      - maven/test
+    - sonar-pr

.github/workflows/maven-ci.yml

@@ -40,25 +40,25 @@ jobs:
     steps:
 
     - name: Checkout Code
-      uses: actions/checkout@v2
+      uses: actions/checkout@master
       with:
         # Disabling shallow clone for improving relevancy of SonarQube reporting
         fetch-depth: 0
 
     - name: Set up JDK 11
-      uses: actions/setup-java@v1
+      uses: actions/setup-java@master
       with:
         java-version: 11
 
     - name: Cache SonarCloud packages
-      uses: actions/cache@v2
+      uses: actions/cache@master
       with:
         path: ~/.sonar/cache
         key: ${{ runner.os }}-sonar
         restore-keys: ${{ runner.os }}-sonar
 
     - name: Cache Maven dependencies
-      uses: actions/cache@v2
+      uses: actions/cache@master
       with:
         path: ~/.m2/repository
         key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
@@ -69,9 +69,6 @@ jobs:
     - name: Install xvfb
       run: sudo apt-get install -y xvfb
 
-    # The SonarQube analysis is only for the master branch of the main repository.
-    # SonarQube scan does not work for forked repositories try changing it to xvfb-run mvn clean verify
-    # See https://jira.sonarsource.com/browse/MMF-1371
     - name: Build with Maven and run SonarQube analysis
       run: xvfb-run ./mvnw clean verify org.sonarsource.scanner.maven:sonar-maven-plugin:sonar
       env:

.github/workflows/maven-pr-builder.yml

@@ -29,7 +29,7 @@ name: Java PR Builder
 on:
   pull_request:
     branches: [ master ]
-    types: [ opened, reopened, synchronize, labeled, unlabeled ]
+    types: [ opened, reopened, synchronize ]
 
 jobs:
   build:
@@ -38,15 +38,15 @@ jobs:
 
     steps:
     - name: Checkout Code
-      uses: actions/checkout@v2
+      uses: actions/checkout@master
     
     - name: Set up JDK 11
-      uses: actions/setup-java@v1
+      uses: actions/setup-java@master
       with:
         java-version: 11
     
     - name: Cache Maven Dependecies
-      uses: actions/cache@v2
+      uses: actions/cache@master
       with:
         path: ~/.m2/repository
         key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
@@ -57,8 +57,5 @@ jobs:
     - name: Install xvfb
       run: sudo apt-get install -y xvfb
     
-    # This worflow is only for building Pull Requests, the master branch runs Sonar analysis on the main repository.
-    # SonarQube scan does not work for forked repositories.
-    # See https://jira.sonarsource.com/browse/MMF-1371
     - name: Build with Maven
       run: xvfb-run ./mvnw clean verify

.mvn/wrapper/MavenWrapperDownloader.java

@@ -1,18 +1,26 @@
 /*
- * Copyright 2007-present the original author or authors.
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
  *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
  *
- *      http://www.apache.org/licenses/LICENSE-2.0
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
  *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
  */
+
 import java.net.*;
 import java.io.*;
 import java.nio.channels.*;

README.md

@@ -10,7 +10,7 @@
 [![Coverage](https://sonarcloud.io/api/project_badges/measure?project=iluwatar_java-design-patterns&metric=coverage)](https://sonarcloud.io/dashboard?id=iluwatar_java-design-patterns)
 [![Join the chat at https://gitter.im/iluwatar/java-design-patterns](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/iluwatar/java-design-patterns?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-154-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-155-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 <br/>
@@ -306,6 +306,7 @@ This project is licensed under the terms of the MIT license.
   <tr>
     <td align="center"><a href="https://github.com/byoungju94"><img src="https://avatars.githubusercontent.com/u/42516378?v=4?s=100" width="100px;" alt=""/><br /><sub><b>byoungju94</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=byoungju94" title="Code">💻</a></td>
     <td align="center"><a href="https://github.com/moustafafarhat"><img src="https://avatars.githubusercontent.com/u/38836727?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Moustafa Farhat</b></sub></a><br /><a href="#translation-moustafafarhat" title="Translation">🌍</a></td>
+    <td align="center"><a href="https://github.com/richardmr36"><img src="https://avatars.githubusercontent.com/u/19147333?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Martel Richard</b></sub></a><br /><a href="https://github.com/iluwatar/java-design-patterns/commits?author=richardmr36" title="Code">💻</a></td>
   </tr>
 </table>
 

arrange-act-assert/pom.xml

@@ -36,8 +36,8 @@
   <artifactId>arrange-act-assert</artifactId>
   <dependencies>
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-engine</artifactId>
       <scope>test</scope>
     </dependency>
   </dependencies>

arrange-act-assert/src/test/java/com/iluwatar/arrangeactassert/CashAAATest.java

@@ -23,11 +23,11 @@
 
 package com.iluwatar.arrangeactassert;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Arrange/Act/Assert (AAA) is a pattern for organizing unit tests. It is a way to structure your
@@ -51,10 +51,11 @@ import org.junit.Test;
  * change and one reason to fail. In a large and complicated code base, tests that honor the single
  * responsibility principle are much easier to troubleshoot.
  */
-public class CashAAATest {
+
+class CashAAATest {
 
   @Test
-  public void testPlus() {
+  void testPlus() {
     //Arrange
     var cash = new Cash(3);
     //Act
@@ -64,7 +65,7 @@ public class CashAAATest {
   }
 
   @Test
-  public void testMinus() {
+  void testMinus() {
     //Arrange
     var cash = new Cash(8);
     //Act
@@ -75,7 +76,7 @@ public class CashAAATest {
   }
 
   @Test
-  public void testInsufficientMinus() {
+  void testInsufficientMinus() {
     //Arrange
     var cash = new Cash(1);
     //Act
@@ -86,7 +87,7 @@ public class CashAAATest {
   }
 
   @Test
-  public void testUpdate() {
+  void testUpdate() {
     //Arrange
     var cash = new Cash(5);
     //Act

arrange-act-assert/src/test/java/com/iluwatar/arrangeactassert/CashAntiAAATest.java

@@ -23,23 +23,24 @@
 
 package com.iluwatar.arrangeactassert;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * ({@link CashAAATest}) is an anti-example of AAA pattern. This test is functionally correct, but
- * with the addition of new feature, it needs refactoring. There are an awful lot of steps in that
+ * with the addition of a new feature, it needs refactoring. There are an awful lot of steps in that
  * test method, but it verifies the class' important behavior in just eleven lines. It violates the
  * single responsibility principle. If this test method failed after a small code change, it might
  * take some digging to discover why.
  */
-public class CashAntiAAATest {
+
+class CashAntiAAATest {
 
   @Test
-  public void testCash() {
+  void testCash() {
     //initialize
     var cash = new Cash(3);
     //test plus

async-method-invocation/pom.xml

@@ -45,11 +45,6 @@
 			<artifactId>mockito-core</artifactId>
 			<scope>test</scope>
 		</dependency>
-		<dependency>
-			<groupId>junit</groupId>
-			<artifactId>junit</artifactId>
-			<scope>test</scope>
-		</dependency>
 	</dependencies>
 	<build>
 		<plugins>

combinator/pom.xml

@@ -34,12 +34,6 @@
 
   <artifactId>combinator</artifactId>
   <dependencies>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <scope>test</scope>
-    </dependency>
-
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter-engine</artifactId>

combinator/src/test/java/com/iluwatar/combinator/CombinatorAppTest.java

@@ -23,11 +23,11 @@
 
 package com.iluwatar.combinator;
 
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
-public class CombinatorAppTest {
+import org.junit.jupiter.api.Test;
+
+class CombinatorAppTest {
 
   /**
    * Issue: Add at least one assertion to this test case.
@@ -37,7 +37,7 @@ public class CombinatorAppTest {
    */
 
   @Test
-  public void shouldExecuteApplicationWithoutException() {
+  void shouldExecuteApplicationWithoutException() {
     assertDoesNotThrow(() -> CombinatorApp.main(new String[]{}));
   }
-}
+}

combinator/src/test/java/com/iluwatar/combinator/FinderTest.java

@@ -23,22 +23,19 @@
 
 package com.iluwatar.combinator;
 
-import org.junit.Assert;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import java.util.List;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.*;
-
-public class FinderTest {
+class FinderTest {
 
   @Test
-  public void contains() {
+  void contains() {
     var example = "the first one \nthe second one \n";
 
     var result = Finder.contains("second").find(example);
-    Assert.assertEquals(result.size(),1);
-    Assert.assertEquals(result.get(0),"the second one ");
+    assertEquals(1, result.size());
+    assertEquals("the second one ", result.get(0));
   }
 
-}
+}

combinator/src/test/java/com/iluwatar/combinator/FindersTest.java

@@ -23,44 +23,44 @@
 
 package com.iluwatar.combinator;
 
-import org.junit.Assert;
-import org.junit.Test;
+import static com.iluwatar.combinator.Finders.advancedFinder;
+import static com.iluwatar.combinator.Finders.expandedFinder;
+import static com.iluwatar.combinator.Finders.filteredFinder;
+import static com.iluwatar.combinator.Finders.specializedFinder;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import java.util.List;
+import org.junit.jupiter.api.Test;
 
-import static com.iluwatar.combinator.Finders.*;
-import static org.junit.Assert.*;
-
-public class FindersTest {
+class FindersTest {
 
   @Test
-  public void advancedFinderTest() {
+  void advancedFinderTest() {
     var res = advancedFinder("it was","kingdom","sea").find(text());
-    Assert.assertEquals(res.size(),1);
-    Assert.assertEquals(res.get(0),"It was many and many a year ago,");
+    assertEquals(1, res.size());
+    assertEquals("It was many and many a year ago,", res.get(0));
   }
 
   @Test
-  public void filteredFinderTest() {
+  void filteredFinderTest() {
     var res = filteredFinder(" was ", "many", "child").find(text());
-    Assert.assertEquals(res.size(),1);
-    Assert.assertEquals(res.get(0),"But we loved with a love that was more than love-");
+    assertEquals(1, res.size());
+    assertEquals("But we loved with a love that was more than love-", res.get(0));
   }
 
   @Test
-  public void specializedFinderTest() {
+  void specializedFinderTest() {
     var res = specializedFinder("love","heaven").find(text());
-    Assert.assertEquals(res.size(),1);
-    Assert.assertEquals(res.get(0),"With a love that the winged seraphs of heaven");
+    assertEquals(1, res.size());
+    assertEquals("With a love that the winged seraphs of heaven", res.get(0));
   }
 
   @Test
-  public void expandedFinderTest() {
+  void expandedFinderTest() {
     var res = expandedFinder("It was","kingdom").find(text());
-    Assert.assertEquals(res.size(),3);
-    Assert.assertEquals(res.get(0),"It was many and many a year ago,");
-    Assert.assertEquals(res.get(1),"In a kingdom by the sea,");
-    Assert.assertEquals(res.get(2),"In this kingdom by the sea;");
+    assertEquals(3, res.size());
+    assertEquals("It was many and many a year ago,", res.get(0));
+    assertEquals("In a kingdom by the sea,", res.get(1));
+    assertEquals("In this kingdom by the sea;", res.get(2));
   }
 
 
@@ -80,4 +80,4 @@ public class FindersTest {
             + "Coveted her and me.";
   }
 
-}
+}

commander/src/main/java/com/iluwatar/commander/Order.java

@@ -23,8 +23,8 @@
 
 package com.iluwatar.commander;
 
+import java.security.SecureRandom;
 import java.util.Hashtable;
-import java.util.Random;
 
 /**
  * Order class holds details of the order.
@@ -45,7 +45,7 @@ public class Order { //can store all transactions ids also
   public final String id;
   final float price;
   final long createdTime;
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
   private static final String ALL_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
   private static final Hashtable<String, Boolean> USED_IDS = new Hashtable<String, Boolean>();
   PaymentStatus paid;

commander/src/main/java/com/iluwatar/commander/Retry.java

@@ -23,10 +23,10 @@
 
 package com.iluwatar.commander;
 
+import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Predicate;
 
@@ -56,7 +56,7 @@ public class Retry<T> {
     void handleIssue(T obj, Exception e);
   }
 
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
 
   private final Operation op;
   private final HandleErrorIssue<T> handleError;

commander/src/main/java/com/iluwatar/commander/Service.java

@@ -24,10 +24,11 @@
 package com.iluwatar.commander;
 
 import com.iluwatar.commander.exceptions.DatabaseUnavailableException;
+
+import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Hashtable;
 import java.util.List;
-import java.util.Random;
 
 /**
  * Service class is an abstract class extended by all services in this example. They all have a
@@ -42,7 +43,7 @@ public abstract class Service {
 
   protected final Database database;
   public ArrayList<Exception> exceptionsList;
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
   private static final String ALL_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
   private static final Hashtable<String, Boolean> USED_IDS = new Hashtable<>();
 

double-buffer/pom.xml

@@ -36,10 +36,6 @@
     <artifactId>double-buffer</artifactId>
 
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-        </dependency>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>

double-buffer/src/test/java/com/iluwatar/doublebuffer/AppTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.doublebuffer;
 
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * App unit test.
  */
-public class AppTest {
+class AppTest {
 
   /**
    * Issue: Add at least one assertion to this test case.
@@ -40,7 +40,7 @@ public class AppTest {
    */
 
   @Test
-  public void shouldExecuteApplicationWithoutException() {
+  void shouldExecuteApplicationWithoutException() {
     assertDoesNotThrow(() -> App.main(new String[]{}));
   }
 

double-buffer/src/test/java/com/iluwatar/doublebuffer/FrameBufferTest.java

@@ -23,17 +23,19 @@
 
 package com.iluwatar.doublebuffer;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
+
 import java.util.Arrays;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * FrameBuffer unit test.
  */
-public class FrameBufferTest {
+class FrameBufferTest {
 
   @Test
-  public void testClearAll() {
+  void testClearAll() {
     try {
       var field = FrameBuffer.class.getDeclaredField("pixels");
       var pixels = new Pixel[FrameBuffer.HEIGHT * FrameBuffer.WIDTH];
@@ -43,14 +45,14 @@ public class FrameBufferTest {
       field.setAccessible(true);
       field.set(frameBuffer, pixels);
       frameBuffer.clearAll();
-      Assert.assertEquals(Pixel.WHITE, frameBuffer.getPixels()[0]);
+      assertEquals(Pixel.WHITE, frameBuffer.getPixels()[0]);
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
   }
 
   @Test
-  public void testClear() {
+  void testClear() {
     try {
       var field = FrameBuffer.class.getDeclaredField("pixels");
       var pixels = new Pixel[FrameBuffer.HEIGHT * FrameBuffer.WIDTH];
@@ -60,21 +62,21 @@ public class FrameBufferTest {
       field.setAccessible(true);
       field.set(frameBuffer, pixels);
       frameBuffer.clear(0, 0);
-      Assert.assertEquals(Pixel.WHITE, frameBuffer.getPixels()[0]);
+      assertEquals(Pixel.WHITE, frameBuffer.getPixels()[0]);
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
   }
 
   @Test
-  public void testDraw() {
+  void testDraw() {
     var frameBuffer = new FrameBuffer();
     frameBuffer.draw(0, 0);
-    Assert.assertEquals(Pixel.BLACK, frameBuffer.getPixels()[0]);
+    assertEquals(Pixel.BLACK, frameBuffer.getPixels()[0]);
   }
 
   @Test
-  public void testGetPixels() {
+  void testGetPixels() {
     try {
       var field = FrameBuffer.class.getDeclaredField("pixels");
       var pixels = new Pixel[FrameBuffer.HEIGHT * FrameBuffer.WIDTH];
@@ -83,9 +85,9 @@ public class FrameBufferTest {
       var frameBuffer = new FrameBuffer();
       field.setAccessible(true);
       field.set(frameBuffer, pixels);
-      Assert.assertEquals(pixels, frameBuffer.getPixels());
+      assertEquals(pixels, frameBuffer.getPixels());
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
   }
 

double-buffer/src/test/java/com/iluwatar/doublebuffer/SceneTest.java

@@ -23,17 +23,19 @@
 
 package com.iluwatar.doublebuffer;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
+
 import java.util.ArrayList;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Scene unit tests.
  */
-public class SceneTest {
+class SceneTest {
 
   @Test
-  public void testGetBuffer() {
+  void testGetBuffer() {
     try {
       var scene = new Scene();
       var field1 = Scene.class.getDeclaredField("current");
@@ -46,14 +48,14 @@ public class SceneTest {
       var field2 = Scene.class.getDeclaredField("frameBuffers");
       field2.setAccessible(true);
       field2.set(scene, frameBuffers);
-      Assert.assertEquals(frameBuffer, scene.getBuffer());
+      assertEquals(frameBuffer, scene.getBuffer());
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to access private field.");
+      fail("Fail to access private field.");
     }
   }
 
   @Test
-  public void testDraw() {
+  void testDraw() {
     try {
       var scene = new Scene();
       var field1 = Scene.class.getDeclaredField("current");
@@ -63,10 +65,10 @@ public class SceneTest {
       field2.setAccessible(true);
       field2.set(scene, 1);
       scene.draw(new ArrayList<>());
-      Assert.assertEquals(1, field1.get(scene));
-      Assert.assertEquals(0, field2.get(scene));
+      assertEquals(1, field1.get(scene));
+      assertEquals(0, field2.get(scene));
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to access private field");
+      fail("Fail to access private field");
     }
   }
 }

event-asynchronous/src/main/java/com/iluwatar/event/asynchronous/EventManager.java

@@ -23,8 +23,8 @@
 
 package com.iluwatar.event.asynchronous;
 
+import java.security.SecureRandom;
 import java.util.Map;
-import java.util.Random;
 import java.util.concurrent.ConcurrentHashMap;
 
 /**
@@ -43,7 +43,7 @@ public class EventManager implements ThreadCompleteListener {
   public static final int MAX_ID = MAX_RUNNING_EVENTS;
   public static final int MAX_EVENT_TIME = 1800; // in seconds / 30 minutes.
   private int currentlyRunningSyncEvent = -1;
-  private final Random rand;
+  private final SecureRandom rand;
   private final Map<Integer, Event> eventPool;
 
   private static final String DOES_NOT_EXIST = " does not exist.";
@@ -52,7 +52,7 @@ public class EventManager implements ThreadCompleteListener {
    * EventManager constructor.
    */
   public EventManager() {
-    rand = new Random(1);
+    rand = new SecureRandom();
     eventPool = new ConcurrentHashMap<Integer, Event>(MAX_RUNNING_EVENTS);
 
   }

factory/pom.xml

@@ -38,10 +38,6 @@
   <artifactId>junit-jupiter-engine</artifactId>
   <scope>test</scope>
  </dependency>
- <dependency>
- <groupId>junit</groupId>
-  <artifactId>junit</artifactId>
- </dependency>
  </dependencies>
  <build>
  <plugins>

game-loop/pom.xml

@@ -35,11 +35,6 @@
 
     <artifactId>game-loop</artifactId>
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-        </dependency>
-
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>

game-loop/src/main/java/com/iluwatar/gameloop/GameLoop.java

@@ -23,7 +23,7 @@
 
 package com.iluwatar.gameloop;
 
-import java.util.Random;
+import java.security.SecureRandom;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -80,7 +80,7 @@ public abstract class GameLoop {
    */
   protected void processInput() {
     try {
-      var lag = new Random().nextInt(200) + 50;
+      var lag = new SecureRandom().nextInt(200) + 50;
       Thread.sleep(lag);
     } catch (InterruptedException e) {
       logger.error(e.getMessage());

half-sync-half-async/pom.xml

@@ -43,11 +43,6 @@
       <artifactId>mockito-core</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
   <build>
     <plugins>

hexagonal/src/main/java/com/iluwatar/hexagonal/domain/LotteryNumbers.java

@@ -24,10 +24,10 @@
 package com.iluwatar.hexagonal.domain;
 
 import com.google.common.base.Joiner;
+import java.security.SecureRandom;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.PrimitiveIterator;
-import java.util.Random;
 import java.util.Set;
 
 /**
@@ -126,7 +126,7 @@ public class LotteryNumbers {
      * @param max the max value (inclusive)
      */
     public RandomNumberGenerator(int min, int max) {
-      randomIterator = new Random().ints(min, max + 1).iterator();
+      randomIterator = new SecureRandom().ints(min, max + 1).iterator();
     }
 
     /**

hexagonal/src/main/java/com/iluwatar/hexagonal/sampledata/SampleData.java

@@ -30,9 +30,9 @@ import com.iluwatar.hexagonal.domain.LotteryService;
 import com.iluwatar.hexagonal.domain.LotteryTicket;
 import com.iluwatar.hexagonal.domain.LotteryTicketId;
 import com.iluwatar.hexagonal.domain.PlayerDetails;
+import java.security.SecureRandom;
 import java.util.AbstractMap.SimpleEntry;
 import java.util.List;
-import java.util.Random;
 import java.util.stream.Collectors;
 
 /**
@@ -41,7 +41,7 @@ import java.util.stream.Collectors;
 public class SampleData {
 
   private static final List<PlayerDetails> PLAYERS;
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
 
   static {
     PLAYERS = List.of(

leader-followers/pom.xml

@@ -32,11 +32,6 @@
     </parent>
     <artifactId>leader-followers</artifactId>
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>

leader-followers/src/main/java/com/iluwatar/leaderfollowers/App.java

@@ -23,7 +23,7 @@
 
 package com.iluwatar.leaderfollowers;
 
-import java.util.Random;
+import java.security.SecureRandom;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 
@@ -84,7 +84,7 @@ public class App {
    * Add tasks.
    */
   private static void addTasks(TaskSet taskSet) throws InterruptedException {
-    var rand = new Random();
+    var rand = new SecureRandom();
     for (var i = 0; i < 5; i++) {
       var time = Math.abs(rand.nextInt(1000));
       taskSet.addTask(new Task(time));

leader-followers/src/test/java/com/AppTest.java

@@ -23,20 +23,20 @@
 
 package com;
 
-import com.iluwatar.leaderfollowers.App;
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
+import com.iluwatar.leaderfollowers.App;
+import org.junit.jupiter.api.Test;
+
 /**
  *
  * Application test
  *
  */
-public class AppTest {
+class AppTest {
 
     @Test
-    public void shouldExecuteApplicationWithoutException() {
+    void shouldExecuteApplicationWithoutException() {
         assertDoesNotThrow(() -> App.main(new String[]{}));
     }
 

leader-followers/src/test/java/com/TaskHandlerTest.java

@@ -23,22 +23,23 @@
 
 package com;
 
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
 import com.iluwatar.leaderfollowers.Task;
 import com.iluwatar.leaderfollowers.TaskHandler;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for TaskHandler
  */
-public class TaskHandlerTest {
+class TaskHandlerTest {
 
     @Test
-    public void testHandleTask() throws InterruptedException {
+    void testHandleTask() throws InterruptedException {
         var taskHandler = new TaskHandler();
         var handle = new Task(100);
         taskHandler.handleTask(handle);
-        Assert.assertTrue(handle.isFinished());
+        assertTrue(handle.isFinished());
     }
 
 }

leader-followers/src/test/java/com/TaskSetTest.java

@@ -23,30 +23,31 @@
 
 package com;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import com.iluwatar.leaderfollowers.Task;
 import com.iluwatar.leaderfollowers.TaskSet;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for TaskSet
  */
-public class TaskSetTest {
+class TaskSetTest {
 
     @Test
-    public void testAddTask() throws InterruptedException {
+    void testAddTask() throws InterruptedException {
         var taskSet = new TaskSet();
         taskSet.addTask(new Task(10));
-        Assert.assertTrue(taskSet.getSize() == 1);
+        assertEquals(1, taskSet.getSize());
     }
 
     @Test
-    public void testGetTask() throws InterruptedException {
+    void testGetTask() throws InterruptedException {
         var taskSet = new TaskSet();
         taskSet.addTask(new Task(100));
         Task task = taskSet.getTask();
-        Assert.assertTrue(task.getTime() == 100);
-        Assert.assertTrue(taskSet.getSize() == 0);
+        assertEquals(100, task.getTime());
+        assertEquals(0, taskSet.getSize());
     }
 
 }

leader-followers/src/test/java/com/WorkCenterTest.java

@@ -23,43 +23,45 @@
 
 package com;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
 import com.iluwatar.leaderfollowers.TaskHandler;
 import com.iluwatar.leaderfollowers.TaskSet;
 import com.iluwatar.leaderfollowers.WorkCenter;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for WorkCenter
  */
-public class WorkCenterTest {
+class WorkCenterTest {
 
   @Test
-  public void testCreateWorkers() {
+  void testCreateWorkers() {
     var taskSet = new TaskSet();
     var taskHandler = new TaskHandler();
     var workCenter = new WorkCenter();
     workCenter.createWorkers(5, taskSet, taskHandler);
-    Assert.assertEquals(workCenter.getWorkers().size(), 5);
-    Assert.assertEquals(workCenter.getWorkers().get(0), workCenter.getLeader());
+    assertEquals(5, workCenter.getWorkers().size());
+    assertEquals(workCenter.getWorkers().get(0), workCenter.getLeader());
   }
 
   @Test
-  public void testNullLeader() {
+  void testNullLeader() {
     var workCenter = new WorkCenter();
     workCenter.promoteLeader();
-    Assert.assertNull(workCenter.getLeader());
+    assertNull(workCenter.getLeader());
   }
 
   @Test
-  public void testPromoteLeader() {
+  void testPromoteLeader() {
     var taskSet = new TaskSet();
     var taskHandler = new TaskHandler();
     var workCenter = new WorkCenter();
     workCenter.createWorkers(5, taskSet, taskHandler);
     workCenter.removeWorker(workCenter.getLeader());
     workCenter.promoteLeader();
-    Assert.assertEquals(workCenter.getWorkers().size(), 4);
-    Assert.assertEquals(workCenter.getWorkers().get(0), workCenter.getLeader());
+    assertEquals(4, workCenter.getWorkers().size());
+    assertEquals(workCenter.getWorkers().get(0), workCenter.getLeader());
   }
 }

marker/src/test/java/GuardTest.java

@@ -21,18 +21,18 @@
  * THE SOFTWARE.
  */
 
-import org.junit.jupiter.api.Test;
-
 import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.hamcrest.MatcherAssert.assertThat;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Guard test
  */
-public class GuardTest {
+class GuardTest {
 
   @Test
-  public void testGuard() {
+  void testGuard() {
     var guard = new Guard();
     assertThat(guard, instanceOf(Permission.class));
   }

master-worker-pattern/src/main/java/com/iluwatar/masterworker/ArrayUtilityMethods.java

@@ -23,7 +23,7 @@
 
 package com.iluwatar.masterworker;
 
-import java.util.Random;
+import java.security.SecureRandom;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -35,7 +35,7 @@ public class ArrayUtilityMethods {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(ArrayUtilityMethods.class);
 
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
 
   /**
    * Method arraysSame compares 2 arrays @param a1 and @param a2 and @return whether their values

mvnw.cmd

@@ -1,21 +1,25 @@
-@REM ----------------------------------------------------------------------------
-@REM Licensed to the Apache Software Foundation (ASF) under one
-@REM or more contributor license agreements.  See the NOTICE file
-@REM distributed with this work for additional information
-@REM regarding copyright ownership.  The ASF licenses this file
-@REM to you under the Apache License, Version 2.0 (the
-@REM "License"); you may not use this file except in compliance
-@REM with the License.  You may obtain a copy of the License at
 @REM
-@REM    http://www.apache.org/licenses/LICENSE-2.0
+@REM The MIT License
+@REM Copyright © 2014-2021 Ilkka Seppälä
+@REM
+@REM Permission is hereby granted, free of charge, to any person obtaining a copy
+@REM of this software and associated documentation files (the "Software"), to deal
+@REM in the Software without restriction, including without limitation the rights
+@REM to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+@REM copies of the Software, and to permit persons to whom the Software is
+@REM furnished to do so, subject to the following conditions:
+@REM
+@REM The above copyright notice and this permission notice shall be included in
+@REM all copies or substantial portions of the Software.
+@REM
+@REM THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+@REM IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+@REM FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+@REM AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+@REM LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+@REM OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+@REM THE SOFTWARE.
 @REM
-@REM Unless required by applicable law or agreed to in writing,
-@REM software distributed under the License is distributed on an
-@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-@REM KIND, either express or implied.  See the License for the
-@REM specific language governing permissions and limitations
-@REM under the License.
-@REM ----------------------------------------------------------------------------
 
 @REM ----------------------------------------------------------------------------
 @REM Maven Start Up Batch script

parameter-object/README.md

@@ -0,0 +1,138 @@
+---
+layout: pattern
+title: Parameter Object
+folder: parameter-object
+permalink: /patterns/parameter-object/
+categories: Behavioral
+tags:
+ - Extensibility
+---
+
+## Intent
+
+The syntax of Java language doesn’t allow you to declare a method with a predefined value
+for a parameter. Probably the best option to achieve default method parameters in Java is
+by using the method overloading. Method overloading allows you to declare several methods
+with the same name but with a different number of parameters. But the main problem with
+method overloading as a solution for default parameter values reveals itself when a method
+accepts multiple parameters. Creating an overloaded method for each possible combination of
+parameters might be cumbersome. To deal with this issue, the Parameter Object pattern is used.
+
+## Explanation
+
+The Parameter Object is simply a wrapper object for all parameters of a method.
+It is nothing more than just a regular POJO. The advantage of the Parameter Object over a
+regular method parameter list is the fact that class fields can have default values.
+Once the wrapper class is created for the method parameter list, a corresponding builder class
+is also created. Usually it's an inner static class. The final step is to use the builder
+to construct a new parameter object. For those parameters that are skipped,
+their default values are going to be used.
+
+
+**Programmatic Example**
+
+Here's the simple `SearchService` class where Method Overloading is used to default values here. To use method overloading, either the number of arguments or argument type has to be different.
+
+```java
+public class SearchService {
+  //Method Overloading example. SortOrder is defaulted in this method
+  public String search(String type, String sortBy) {
+    return getQuerySummary(type, sortBy, SortOrder.DESC);
+  }
+
+  /* Method Overloading example. SortBy is defaulted in this method. Note that the type has to be 
+  different here to overload the method */
+  public String search(String type, SortOrder sortOrder) {
+    return getQuerySummary(type, "price", sortOrder);
+  }
+
+  private String getQuerySummary(String type, String sortBy, SortOrder sortOrder) {
+    return "Requesting shoes of type \"" + type + "\" sorted by \"" + sortBy + "\" in \""
+        + sortOrder.getValue() + "ending\" order...";
+  }
+}
+
+```
+
+Next we present the `SearchService` with `ParameterObject` created with Builder pattern.
+
+```java
+public class SearchService {
+
+  /* Parameter Object example. Default values are abstracted into the Parameter Object 
+  at the time of Object creation */
+  public String search(ParameterObject parameterObject) {
+    return getQuerySummary(parameterObject.getType(), parameterObject.getSortBy(),
+        parameterObject.getSortOrder());
+  }
+  
+  private String getQuerySummary(String type, String sortBy, SortOrder sortOrder) {
+    return "Requesting shoes of type \"" + type + "\" sorted by \"" + sortBy + "\" in \""
+        + sortOrder.getValue() + "ending\" order...";
+  }
+}
+
+public class ParameterObject {
+  public static final String DEFAULT_SORT_BY = "price";
+  public static final SortOrder DEFAULT_SORT_ORDER = SortOrder.ASC;
+
+  private String type;
+  private String sortBy = DEFAULT_SORT_BY;
+  private SortOrder sortOrder = DEFAULT_SORT_ORDER;
+
+  private ParameterObject(Builder builder) {
+    type = builder.type;
+    sortBy = builder.sortBy != null && !builder.sortBy.isBlank() ? builder.sortBy : sortBy;
+    sortOrder = builder.sortOrder != null ? builder.sortOrder : sortOrder;
+  }
+
+  public static Builder newBuilder() {
+    return new Builder();
+  }
+
+  //Getters and Setters...
+
+  public static final class Builder {
+
+    private String type;
+    private String sortBy;
+    private SortOrder sortOrder;
+
+    private Builder() {
+    }
+
+    public Builder withType(String type) {
+      this.type = type;
+      return this;
+    }
+
+    public Builder sortBy(String sortBy) {
+      this.sortBy = sortBy;
+      return this;
+    }
+
+    public Builder sortOrder(SortOrder sortOrder) {
+      this.sortOrder = sortOrder;
+      return this;
+    }
+
+    public ParameterObject build() {
+      return new ParameterObject(this);
+    }
+  }
+}
+
+
+```
+
+## Class diagram
+
+![alt text](./etc/parameter-object.png "Parameter Object")
+
+## Applicability
+
+This pattern shows us the way to have default parameters for a method in Java as the language doesn't default parameters feature out of the box. 
+
+## Credits
+
+- [Does Java have default parameters?](http://dolszewski.com/java/java-default-parameters)

parameter-object/etc/parameter-object.urm.puml

@@ -0,0 +1,52 @@
+@startuml
+package com.iluwatar.parameter.object {
+  class App {
+    - LOGGER : Logger {static}
+    + App()
+    + main(args : String[]) {static}
+  }
+  class ParameterObject {
+    + DEFAULT_SORT_BY : String {static}
+    + DEFAULT_SORT_ORDER : SortOrder {static}
+    - sortBy : String
+    - sortOrder : SortOrder
+    - type : String
+    - ParameterObject(builder : Builder)
+    + getSortBy() : String
+    + getSortOrder() : SortOrder
+    + getType() : String
+    + newBuilder() : Builder {static}
+    + setSortBy(sortBy : String)
+    + setSortOrder(sortOrder : SortOrder)
+    + setType(type : String)
+  }
+  class Builder {
+    - sortBy : String
+    - sortOrder : SortOrder
+    - type : String
+    - Builder()
+    + build() : ParameterObject
+    + sortBy(sortBy : String) : Builder
+    + sortOrder(sortOrder : SortOrder) : Builder
+    + withType(type : String) : Builder
+  }
+  class SearchService {
+    + SearchService()
+    - getQuerySummary(type : String, sortBy : String, sortOrder : SortOrder) : String
+    + search(parameterObject : ParameterObject) : String
+    + search(type : String, sortBy : String) : String
+    + search(type : String, sortOrder : SortOrder) : String
+  }
+  enum SortOrder {
+    + ASC {static}
+    + DESC {static}
+    - value : String
+    + getValue() : String
+    + valueOf(name : String) : SortOrder {static}
+    + values() : SortOrder[] {static}
+  }
+}
+Builder -->  "-sortOrder" SortOrder
+Builder ..+ ParameterObject
+ParameterObject -->  "-DEFAULT_SORT_ORDER" SortOrder
+@enduml

parameter-object/pom.xml

@@ -0,0 +1,61 @@
+<?xml version="1.0"?>
+<!--
+
+    The MIT License
+    Copyright © 2014-2021 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>com.iluwatar</groupId>
+    <artifactId>java-design-patterns</artifactId>
+    <version>1.24.0-SNAPSHOT</version>
+  </parent>
+  <artifactId>parameter-object</artifactId>
+  <dependencies>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter-engine</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-assembly-plugin</artifactId>
+        <executions>
+          <execution>
+            <configuration>
+              <archive>
+                <manifest>
+                  <mainClass>com.iluwatar.parameter.object.App</mainClass>
+                </manifest>
+              </archive>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

parameter-object/src/main/java/com/iluwatar/parameter/object/App.java

@@ -0,0 +1,62 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.parameter.object;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * The syntax of Java language doesn’t allow you to declare a method with a predefined value
+ * for a parameter. Probably the best option to achieve default method parameters in Java is
+ * by using the method overloading. Method overloading allows you to declare several methods
+ * with the same name but with a different number of parameters. But the main problem with
+ * method overloading as a solution for default parameter values reveals itself when a method
+ * accepts multiple parameters. Creating an overloaded method for each possible combination of
+ * parameters might be cumbersome. To deal with this issue, the Parameter Object pattern is used.
+ * The Parameter Object is simply a wrapper object for all parameters of a method.
+ * It is nothing more than just a regular POJO. The advantage of the Parameter Object over a
+ * regular method parameter list is the fact that class fields can have default values.
+ * Once the wrapper class is created for the method parameter list, a corresponding builder class
+ * is also created. Usually it's an inner static class. The final step is to use the builder
+ * to construct a new parameter object. For those parameters that are skipped,
+ * their default values are going to be used.
+ */
+public class App {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
+  /**
+   * Program entry point.
+   *
+   * @param args command line args
+   */
+  public static void main(String[] args) {
+    ParameterObject params = ParameterObject.newBuilder()
+        .withType("sneakers")
+        .sortBy("brand")
+        .build();
+    LOGGER.info(params.toString());
+    LOGGER.info(new SearchService().search(params));
+  }
+}

parameter-object/src/main/java/com/iluwatar/parameter/object/ParameterObject.java

@@ -0,0 +1,113 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.parameter.object;
+
+public class ParameterObject {
+
+  /**
+   * Default values are defined here.
+   */
+  public static final String DEFAULT_SORT_BY = "price";
+  public static final SortOrder DEFAULT_SORT_ORDER = SortOrder.ASC;
+
+  private String type;
+
+  /**
+   * Default values are assigned here.
+   */
+  private String sortBy = DEFAULT_SORT_BY;
+  private SortOrder sortOrder = DEFAULT_SORT_ORDER;
+
+  /**
+   * Overriding default values on object creation only when builder object has a valid value.
+   */
+  private ParameterObject(Builder builder) {
+    setType(builder.type);
+    setSortBy(builder.sortBy != null && !builder.sortBy.isBlank() ? builder.sortBy : sortBy);
+    setSortOrder(builder.sortOrder != null ? builder.sortOrder : sortOrder);
+  }
+
+  public static Builder newBuilder() {
+    return new Builder();
+  }
+
+  public String getType() {
+    return type;
+  }
+
+  public void setType(String type) {
+    this.type = type;
+  }
+
+  public String getSortBy() {
+    return sortBy;
+  }
+
+  public void setSortBy(String sortBy) {
+    this.sortBy = sortBy;
+  }
+
+  public SortOrder getSortOrder() {
+    return sortOrder;
+  }
+
+  public void setSortOrder(SortOrder sortOrder) {
+    this.sortOrder = sortOrder;
+  }
+
+  @Override
+  public String toString() {
+    return String.format("ParameterObject[type='%s', sortBy='%s', sortOrder='%s']",
+        type, sortBy, sortOrder);
+  }
+
+  public static final class Builder {
+
+    private String type;
+    private String sortBy;
+    private SortOrder sortOrder;
+
+    private Builder() {
+    }
+
+    public Builder withType(String type) {
+      this.type = type;
+      return this;
+    }
+
+    public Builder sortBy(String sortBy) {
+      this.sortBy = sortBy;
+      return this;
+    }
+
+    public Builder sortOrder(SortOrder sortOrder) {
+      this.sortOrder = sortOrder;
+      return this;
+    }
+
+    public ParameterObject build() {
+      return new ParameterObject(this);
+    }
+  }
+}

parameter-object/src/main/java/com/iluwatar/parameter/object/SearchService.java

@@ -0,0 +1,60 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.parameter.object;
+
+public class SearchService {
+
+  /**
+   * Below two methods of name `search` is overloaded so that we can send a default value for
+   * one of the criteria and call the final api. A default SortOrder is sent in the first method
+   * and a default SortBy is sent in the second method. So two separate method definitions are
+   * needed for having default values for one argument in each case. Hence multiple overloaded
+   * methods are needed as the number of argument increases.
+   */
+  public String search(String type, String sortBy) {
+    return getQuerySummary(type, sortBy, SortOrder.ASC);
+  }
+
+  public String search(String type, SortOrder sortOrder) {
+    return getQuerySummary(type, "price", sortOrder);
+  }
+
+
+  /**
+   * The need for multiple method definitions can be avoided by the Parameter Object pattern.
+   * Below is the example where only one method is required and all the logic for having default
+   * values are abstracted into the Parameter Object at the time of object creation.
+   */
+  public String search(ParameterObject parameterObject) {
+    return getQuerySummary(parameterObject.getType(), parameterObject.getSortBy(),
+        parameterObject.getSortOrder());
+  }
+
+  private String getQuerySummary(String type, String sortBy, SortOrder sortOrder) {
+    return String.format("Requesting shoes of type \"%s\" sorted by \"%s\" in \"%sending\" order..",
+        type,
+        sortBy,
+        sortOrder.getValue());
+  }
+}

parameter-object/src/main/java/com/iluwatar/parameter/object/SortOrder.java

@@ -0,0 +1,39 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.parameter.object;
+
+public enum SortOrder {
+  ASC("asc"),
+  DESC("desc");
+
+  private String value;
+
+  SortOrder(String value) {
+    this.value = value;
+  }
+
+  public String getValue() {
+    return value;
+  }
+}

parameter-object/src/test/java/com/iluwatar/parameter/object/AppTest.java

@@ -0,0 +1,41 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.parameter.object;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Application test
+ */
+class AppTest {
+  private static final Logger LOGGER = LoggerFactory.getLogger(AppTest.class);
+
+  @Test
+  void shouldExecuteApplicationWithoutException() {
+    App.main(new String[]{});
+    LOGGER.info("Executed successfully without exception.");
+  }
+}

parameter-object/src/test/java/com/iluwatar/parameter/object/ParameterObjectTest.java

@@ -0,0 +1,63 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.parameter.object;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class ParameterObjectTest {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(ParameterObjectTest.class);
+
+  @Test
+  public void testForDefaultSortBy() {
+    //Creating parameter object with default value for SortBy set
+    ParameterObject params = ParameterObject.newBuilder()
+        .withType("sneakers")
+        .sortOrder(SortOrder.DESC)
+        .build();
+
+    assertEquals(ParameterObject.DEFAULT_SORT_BY, params.getSortBy(),
+        "Default SortBy is not set.");
+    LOGGER.info("{} Default parameter value is set during object creation as no value is passed."
+        , "SortBy");
+  }
+
+  @Test
+  public void testForDefaultSortOrder() {
+    //Creating parameter object with default value for SortOrder set
+    ParameterObject params = ParameterObject.newBuilder()
+        .withType("sneakers")
+        .sortBy("brand")
+        .build();
+
+    assertEquals(ParameterObject.DEFAULT_SORT_ORDER, params.getSortOrder(),
+        "Default SortOrder is not set.");
+    LOGGER.info("{} Default parameter value is set during object creation as no value is passed."
+        , "SortOrder");
+  }
+}

parameter-object/src/test/java/com/iluwatar/parameter/object/SearchServiceTest.java

@@ -0,0 +1,63 @@
+/*
+ * The MIT License
+ * Copyright © 2014-2021 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.parameter.object;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class SearchServiceTest {
+  private static final Logger LOGGER = LoggerFactory.getLogger(SearchServiceTest.class);
+  private ParameterObject parameterObject;
+  private SearchService searchService;
+
+  @BeforeEach
+  public void setUp() {
+    //Creating parameter object with default values set
+    parameterObject = ParameterObject.newBuilder()
+        .withType("sneakers")
+        .build();
+
+    searchService = new SearchService();
+  }
+
+  /**
+   *  Testing parameter object against the overloaded method to verify if the behaviour is same.
+   */
+  @Test
+  public void testDefaultParametersMatch() {
+    assertEquals(searchService.search(parameterObject), searchService.search("sneakers",
+        SortOrder.ASC), "Default Parameter values do not not match.");
+    LOGGER.info("SortBy Default parameter value matches.");
+
+    assertEquals(searchService.search(parameterObject), searchService.search("sneakers",
+        "price"), "Default Parameter values do not not match.");
+    LOGGER.info("SortOrder Default parameter value matches.");
+
+    LOGGER.info("testDefaultParametersMatch executed successfully without errors.");
+  }
+}

partial-response/pom.xml

@@ -35,12 +35,6 @@
 
     <artifactId>partial-response</artifactId>
     <dependencies>
-        <dependency>
-            <groupId>org.junit.vintage</groupId>
-            <artifactId>junit-vintage-engine</artifactId>
-            <version>5.4.0</version>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-junit-jupiter</artifactId>

partial-response/src/test/java/com/iluwatar/partialresponse/VideoResourceTest.java

@@ -23,17 +23,18 @@
 
 package com.iluwatar.partialresponse;
 
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+
+import java.util.Map;
 import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
-import org.mockito.Matchers;
 import org.mockito.Mock;
 import org.mockito.Mockito;
 import org.mockito.junit.jupiter.MockitoExtension;
 
-import java.util.Map;
-
 /**
  * tests {@link VideoResource}.
  */
@@ -44,8 +45,8 @@ class VideoResourceTest {
 
   private static VideoResource resource;
 
-  @BeforeAll
-  static void setUp() {
+  @BeforeEach
+  void setUp() {
     var videos = Map.of(
         1, new Video(1, "Avatar", 178, "epic science fiction film",
             "James Cameron", "English"),
@@ -70,7 +71,7 @@ class VideoResourceTest {
     var fields = new String[]{"id", "title", "length"};
 
     var expectedDetails = "{\"id\": 1,\"title\": \"Avatar\",\"length\": 178}";
-    Mockito.when(fieldJsonMapper.toJson(Matchers.any(Video.class), Matchers.eq(fields))).thenReturn(expectedDetails);
+    Mockito.when(fieldJsonMapper.toJson(any(Video.class), eq(fields))).thenReturn(expectedDetails);
 
     var actualFieldsDetails = resource.getDetails(2, fields);
 

pom.xml

@@ -41,8 +41,8 @@
         <spring-data.version>2.0.14.RELEASE</spring-data.version>
         <h2.version>1.4.190</h2.version>
         <junit.version>4.12</junit.version>
-        <junit-jupiter.version>5.5.2</junit-jupiter.version>
-        <junit-vintage.version>${junit.version}.2</junit-vintage.version>
+        <junit-jupiter.version>5.7.1</junit-jupiter.version>
+        <junit-vintage.version>${junit-jupiter.version}</junit-vintage.version>
         <sping-test-junit5.version>1.0.2</sping-test-junit5.version>
         <compiler.version>3.8.1</compiler.version>
         <jacoco.version>0.8.6</jacoco.version>
@@ -208,6 +208,7 @@
         <module>factory</module>
         <module>separated-interface</module>
         <module>special-case</module>
+        <module>parameter-object</module>
     </modules>
 
     <repositories>
@@ -273,12 +274,6 @@
                 <artifactId>camel-stream</artifactId>
                 <version>${camel.version}</version>
             </dependency>
-            <dependency>
-                <groupId>junit</groupId>
-                <artifactId>junit</artifactId>
-                <version>${junit.version}</version>
-                <scope>test</scope>
-            </dependency>
             <dependency>
                 <groupId>org.junit.jupiter</groupId>
                 <artifactId>junit-jupiter-api</artifactId>

producer-consumer/src/main/java/com/iluwatar/producer/consumer/Producer.java

@@ -23,7 +23,7 @@
 
 package com.iluwatar.producer.consumer;
 
-import java.util.Random;
+import java.security.SecureRandom;
 
 /**
  * Class responsible for producing unit of work that can be expressed as {@link Item} and submitted
@@ -31,7 +31,7 @@ import java.util.Random;
  */
 public class Producer {
 
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
 
   private final ItemQueue queue;
 

registry/pom.xml

@@ -41,10 +41,6 @@
       <artifactId>junit-jupiter-engine</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-    </dependency>
   </dependencies>
 
   <build>

role-object/pom.xml

@@ -34,11 +34,6 @@
 
   <artifactId>role-object</artifactId>
   <dependencies>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter-engine</artifactId>

role-object/src/test/java/com/iluwatar/roleobject/ApplicationRoleObjectTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.roleobject;
 
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
-public class ApplicationRoleObjectTest {
+import org.junit.jupiter.api.Test;
+
+class ApplicationRoleObjectTest {
 
   @Test
-  public void shouldExecuteApplicationWithoutException() {
+  void shouldExecuteApplicationWithoutException() {
     assertDoesNotThrow(() -> ApplicationRoleObject.main(new String[]{}));
   }
 }

role-object/src/test/java/com/iluwatar/roleobject/BorrowerRoleTest.java

@@ -23,15 +23,16 @@
 
 package com.iluwatar.roleobject;
 
-import org.junit.Assert;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
-public class BorrowerRoleTest {
+import org.junit.jupiter.api.Test;
+
+class BorrowerRoleTest {
 
   @Test
-  public void borrowTest() {
+  void borrowTest() {
     var borrowerRole = new BorrowerRole();
     borrowerRole.setName("test");
-    Assert.assertEquals(borrowerRole.borrow(), "Borrower test wants to get some money.");
+    assertEquals("Borrower test wants to get some money.", borrowerRole.borrow());
   }
 }

role-object/src/test/java/com/iluwatar/roleobject/CustomerCoreTest.java

@@ -23,22 +23,22 @@
 
 package com.iluwatar.roleobject;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-public class CustomerCoreTest {
+class CustomerCoreTest {
 
   @Test
-  public void addRole() {
+  void addRole() {
     var core = new CustomerCore();
     assertTrue(core.addRole(Role.Borrower));
   }
 
   @Test
-  public void hasRole() {
+  void hasRole() {
     var core = new CustomerCore();
     core.addRole(Role.Borrower);
     assertTrue(core.hasRole(Role.Borrower));
@@ -46,7 +46,7 @@ public class CustomerCoreTest {
   }
 
   @Test
-  public void remRole() {
+  void remRole() {
     var core = new CustomerCore();
     core.addRole(Role.Borrower);
 
@@ -60,7 +60,7 @@ public class CustomerCoreTest {
   }
 
   @Test
-  public void getRole() {
+  void getRole() {
     var core = new CustomerCore();
     core.addRole(Role.Borrower);
 
@@ -76,17 +76,17 @@ public class CustomerCoreTest {
 
 
   @Test
-  public void toStringTest() {
+  void toStringTest() {
     var core = new CustomerCore();
     core.addRole(Role.Borrower);
-    assertEquals(core.toString(), "Customer{roles=[Borrower]}");
+    assertEquals("Customer{roles=[Borrower]}", core.toString());
 
     core = new CustomerCore();
     core.addRole(Role.Investor);
-    assertEquals(core.toString(), "Customer{roles=[Investor]}");
+    assertEquals("Customer{roles=[Investor]}", core.toString());
 
     core = new CustomerCore();
-    assertEquals(core.toString(), "Customer{roles=[]}");
+    assertEquals("Customer{roles=[]}", core.toString());
 
 
   }

role-object/src/test/java/com/iluwatar/roleobject/InvestorRoleTest.java

@@ -23,16 +23,17 @@
 
 package com.iluwatar.roleobject;
 
-import org.junit.Assert;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
-public class InvestorRoleTest {
+import org.junit.jupiter.api.Test;
+
+class InvestorRoleTest {
 
   @Test
-  public void investTest() {
+  void investTest() {
     var investorRole = new InvestorRole();
     investorRole.setName("test");
     investorRole.setAmountToInvest(10);
-    Assert.assertEquals(investorRole.invest(), "Investor test has invested 10 dollars");
+    assertEquals("Investor test has invested 10 dollars", investorRole.invest());
   }
 }

role-object/src/test/java/com/iluwatar/roleobject/RoleTest.java

@@ -23,15 +23,17 @@
 
 package com.iluwatar.roleobject;
 
-import org.junit.Assert;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-public class RoleTest {
+import org.junit.jupiter.api.Test;
+
+class RoleTest {
 
   @Test
-  public void instanceTest() {
+  void instanceTest() {
     var instance = Role.Borrower.instance();
-    Assert.assertTrue(instance.isPresent());
-    Assert.assertEquals(instance.get().getClass(), BorrowerRole.class);
+    assertTrue(instance.isPresent());
+    assertEquals(instance.get().getClass(), BorrowerRole.class);
   }
 }

saga/pom.xml

@@ -35,11 +35,6 @@
 
     <artifactId>saga</artifactId>
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>

saga/src/test/java/com/iluwatar/saga/choreography/SagaApplicationTest.java

@@ -23,18 +23,19 @@
 
 package com.iluwatar.saga.choreography;
 
-import com.iluwatar.saga.orchestration.SagaApplication;
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
+import com.iluwatar.saga.orchestration.SagaApplication;
+import org.junit.jupiter.api.Test;
+
 
 /***
  * empty test
  */
-public class SagaApplicationTest {
+class SagaApplicationTest {
+
   @Test
-  public void shouldExecuteWithoutException() {
+  void shouldExecuteWithoutException() {
     assertDoesNotThrow(() -> SagaApplication.main(new String[]{}));
   }
-}
+}

saga/src/test/java/com/iluwatar/saga/choreography/SagaChoreographyTest.java

@@ -23,24 +23,25 @@
 
 package com.iluwatar.saga.choreography;
 
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
  * test to check choreography saga
  */
-public class SagaChoreographyTest {
+class SagaChoreographyTest {
 
 
   @Test
-  public void executeTest() {
+  void executeTest() {
     var sd = serviceDiscovery();
     var service = sd.findAny();
     var badOrderSaga = service.execute(newSaga("bad_order"));
     var goodOrderSaga = service.execute(newSaga("good_order"));
 
-    Assert.assertEquals(badOrderSaga.getResult(), Saga.SagaResult.ROLLBACKED);
-    Assert.assertEquals(goodOrderSaga.getResult(), Saga.SagaResult.FINISHED);
+    assertEquals(Saga.SagaResult.ROLLBACKED, badOrderSaga.getResult());
+    assertEquals(Saga.SagaResult.FINISHED, goodOrderSaga.getResult());
   }
 
   private static Saga newSaga(Object value) {

saga/src/test/java/com/iluwatar/saga/orchestration/SagaApplicationTest.java

@@ -23,15 +23,15 @@
 
 package com.iluwatar.saga.orchestration;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * empty test
  */
-public class SagaApplicationTest {
+class SagaApplicationTest {
 
   @Test
-  public void mainTest() {
+  void mainTest() {
     SagaApplication.main(new String[]{});
   }
-}
+}

saga/src/test/java/com/iluwatar/saga/orchestration/SagaOrchestratorInternallyTest.java

@@ -23,28 +23,30 @@
 
 package com.iluwatar.saga.orchestration;
 
+import org.junit.jupiter.api.Test;
+
 import static com.iluwatar.saga.orchestration.Saga.Result;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.ArrayList;
 import java.util.List;
-import org.junit.Assert;
-import org.junit.Test;
 
 /**
  * test to test orchestration logic
  */
-public class SagaOrchestratorInternallyTest {
+class SagaOrchestratorInternallyTest {
 
   private final List<String> records = new ArrayList<>();
 
   @Test
-  public void executeTest() {
+  void executeTest() {
     var sagaOrchestrator = new SagaOrchestrator(newSaga(), serviceDiscovery());
     var result = sagaOrchestrator.execute(1);
-    Assert.assertEquals(result, Result.ROLLBACK);
-    Assert.assertArrayEquals(
-        records.toArray(new String[]{}),
-        new String[]{"+1", "+2", "+3", "+4", "-4", "-3", "-2", "-1"});
+    assertEquals(Result.ROLLBACK, result);
+    assertArrayEquals(
+            new String[]{"+1", "+2", "+3", "+4", "-4", "-3", "-2", "-1"},
+            records.toArray(new String[]{}));
   }
 
   private static Saga newSaga() {

saga/src/test/java/com/iluwatar/saga/orchestration/SagaOrchestratorTest.java

@@ -23,22 +23,23 @@
 
 package com.iluwatar.saga.orchestration;
 
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
  * test to check general logic
  */
-public class SagaOrchestratorTest {
+class SagaOrchestratorTest {
 
   @Test
-  public void execute() {
+  void execute() {
     SagaOrchestrator sagaOrchestrator = new SagaOrchestrator(newSaga(), serviceDiscovery());
     Saga.Result badOrder = sagaOrchestrator.execute("bad_order");
     Saga.Result crashedOrder = sagaOrchestrator.execute("crashed_order");
 
-    Assert.assertEquals(badOrder, Saga.Result.ROLLBACK);
-    Assert.assertEquals(crashedOrder, Saga.Result.CRASHED);
+    assertEquals(Saga.Result.ROLLBACK, badOrder);
+    assertEquals(Saga.Result.CRASHED, crashedOrder);
   }
 
   private static Saga newSaga() {

serverless/src/test/java/com/iluwatar/serverless/faas/api/LambdaInfoApiHandlerTest.java

@@ -30,17 +30,14 @@ import static org.mockito.Mockito.when;
 
 import com.amazonaws.services.lambda.runtime.Context;
 import org.junit.jupiter.api.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
 
 /**
  * Unit tests for LambdaInfoApiHandler
  */
-@RunWith(MockitoJUnitRunner.class)
-public class LambdaInfoApiHandlerTest {
+class LambdaInfoApiHandlerTest {
 
   @Test
-  public void handleRequestWithMockContext() {
+  void handleRequestWithMockContext() {
     var lambdaInfoApiHandler = new LambdaInfoApiHandler();
     var context = mock(Context.class);
     when(context.getAwsRequestId()).thenReturn("mock aws request id");

sharding/pom.xml

@@ -36,10 +36,6 @@
     <artifactId>sharding</artifactId>
 
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>

sharding/src/main/java/com/iluwatar/sharding/LookupShardManager.java

@@ -23,9 +23,9 @@
 
 package com.iluwatar.sharding;
 
+import java.security.SecureRandom;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Random;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -58,7 +58,7 @@ public class LookupShardManager extends ShardManager {
       return lookupMap.get(key);
     } else {
       var shardCount = shardMap.size();
-      return new Random().nextInt(shardCount - 1) + 1;
+      return new SecureRandom().nextInt(shardCount - 1) + 1;
     }
   }
 

sharding/src/test/java/com/iluwatar/sharding/AppTest.java

@@ -23,17 +23,17 @@
 
 package com.iluwatar.sharding;
 
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Unit tests for App class.
  */
-public class AppTest {
+class AppTest {
 
   @Test
-  public void shouldExecuteWithoutException() {
+  void shouldExecuteWithoutException() {
     assertDoesNotThrow(() -> App.main(new String[]{}));
   }
 

sharding/src/test/java/com/iluwatar/sharding/HashShardManagerTest.java

@@ -23,22 +23,22 @@
 
 package com.iluwatar.sharding;
 
-import org.junit.After;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * Unit tests for HashShardManager class.
  */
-public class HashShardManagerTest {
+class HashShardManagerTest {
 
   private HashShardManager hashShardManager;
 
   /**
    * Initialize hashShardManager instance.
    */
-  @Before
+  @BeforeEach
   public void setup() {
     hashShardManager = new HashShardManager();
     var shard1 = new Shard(1);
@@ -49,16 +49,11 @@ public class HashShardManagerTest {
     hashShardManager.addNewShard(shard3);
   }
 
-  @After
-  public void tearDown() {
-
-  }
-
   @Test
-  public void testStoreData() {
+  void testStoreData() {
     var data = new Data(1, "test", Data.DataType.TYPE_1);
     hashShardManager.storeData(data);
-    Assert.assertEquals(data, hashShardManager.getShardById(1).getDataById(1));
+    assertEquals(data, hashShardManager.getShardById(1).getDataById(1));
   }
 
 }

sharding/src/test/java/com/iluwatar/sharding/LookupShardManagerTest.java

@@ -23,22 +23,24 @@
 
 package com.iluwatar.sharding;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
+
 import java.util.Map;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * Unit tests for LookupShardManager class.
  */
-public class LookupShardManagerTest {
+class LookupShardManagerTest {
 
   private LookupShardManager lookupShardManager;
 
   /**
    * Initialize lookupShardManager instance.
    */
-  @Before
+  @BeforeEach
   public void setup() {
     lookupShardManager = new LookupShardManager();
     var shard1 = new Shard(1);
@@ -50,7 +52,7 @@ public class LookupShardManagerTest {
   }
 
   @Test
-  public void testStoreData() {
+  void testStoreData() {
     try {
       var data = new Data(1, "test", Data.DataType.TYPE_1);
       lookupShardManager.storeData(data);
@@ -59,9 +61,9 @@ public class LookupShardManagerTest {
       var lookupMap = (Map<Integer, Integer>) field.get(lookupShardManager);
       var shardId = lookupMap.get(1);
       var shard = lookupShardManager.getShardById(shardId);
-      Assert.assertEquals(data, shard.getDataById(1));
+      assertEquals(data, shard.getDataById(1));
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
   }
 }

sharding/src/test/java/com/iluwatar/sharding/RangeShardManagerTest.java

@@ -23,21 +23,22 @@
 
 package com.iluwatar.sharding;
 
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * Unit tests for RangeShardManager class.
  */
-public class RangeShardManagerTest {
+class RangeShardManagerTest {
 
   private RangeShardManager rangeShardManager;
 
   /**
    * Initialize rangeShardManager instance.
    */
-  @Before
+  @BeforeEach
   public void setup() {
     rangeShardManager = new RangeShardManager();
     var shard1 = new Shard(1);
@@ -49,10 +50,10 @@ public class RangeShardManagerTest {
   }
 
   @Test
-  public void testStoreData() {
+  void testStoreData() {
     var data = new Data(1, "test", Data.DataType.TYPE_1);
     rangeShardManager.storeData(data);
-    Assert.assertEquals(data, rangeShardManager.getShardById(1).getDataById(1));
+    assertEquals(data, rangeShardManager.getShardById(1).getDataById(1));
   }
 
 }

sharding/src/test/java/com/iluwatar/sharding/ShardManagerTest.java

@@ -23,49 +23,46 @@
 
 package com.iluwatar.sharding;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
+
 import java.util.Map;
-import org.junit.After;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * Unit tests for ShardManager class.
  */
-public class ShardManagerTest {
+class ShardManagerTest {
 
   private ShardManager shardManager;
 
   /**
    * Initialize shardManager instance.
    */
-  @Before
-  public void setup() {
+  @BeforeEach
+  void setup() {
     shardManager = new TestShardManager();
   }
 
-  @After
-  public void tearDown() {
-
-  }
-
   @Test
-  public void testAddNewShard() {
+  void testAddNewShard() {
     try {
       var shard = new Shard(1);
       shardManager.addNewShard(shard);
       var field = ShardManager.class.getDeclaredField("shardMap");
       field.setAccessible(true);
       var map = (Map<Integer, Shard>) field.get(shardManager);
-      Assert.assertEquals(1, map.size());
-      Assert.assertEquals(shard, map.get(1));
+      assertEquals(1, map.size());
+      assertEquals(shard, map.get(1));
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
   }
 
   @Test
-  public void testRemoveShardById() {
+  void testRemoveShardById() {
     try {
       var shard = new Shard(1);
       shardManager.addNewShard(shard);
@@ -73,19 +70,19 @@ public class ShardManagerTest {
       var field = ShardManager.class.getDeclaredField("shardMap");
       field.setAccessible(true);
       var map = (Map<Integer, Shard>) field.get(shardManager);
-      Assert.assertEquals(true, flag);
-      Assert.assertEquals(0, map.size());
+      assertTrue(flag);
+      assertEquals(0, map.size());
     } catch (IllegalAccessException | NoSuchFieldException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
   }
 
   @Test
-  public void testGetShardById() {
+  void testGetShardById() {
     var shard = new Shard(1);
     shardManager.addNewShard(shard);
     var tmpShard = shardManager.getShardById(1);
-    Assert.assertEquals(shard, tmpShard);
+    assertEquals(shard, tmpShard);
   }
 
   class TestShardManager extends ShardManager {

sharding/src/test/java/com/iluwatar/sharding/ShardTest.java

@@ -23,50 +23,47 @@
 
 package com.iluwatar.sharding;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
+
 import java.util.HashMap;
 import java.util.Map;
-import org.junit.After;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 
 /**
  * Unit tests for Shard class.
  */
-public class ShardTest {
+class ShardTest {
 
   private Data data;
 
   private Shard shard;
 
-  @Before
+  @BeforeEach
   public void setup() {
     data = new Data(1, "test", Data.DataType.TYPE_1);
     shard = new Shard(1);
   }
 
-  @After
-  public void tearDown() {
-  }
-
   @Test
-  public void testStoreData() {
+  void testStoreData() {
     try {
       shard.storeData(data);
       var field = Shard.class.getDeclaredField("dataStore");
       field.setAccessible(true);
       var dataMap = (Map<Integer, Data>) field.get(shard);
-      Assert.assertEquals(1, dataMap.size());
-      Assert.assertEquals(data, dataMap.get(1));
+      assertEquals(1, dataMap.size());
+      assertEquals(data, dataMap.get(1));
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
 
   }
 
   @Test
-  public void testClearData() {
+  void testClearData() {
     try {
       var dataMap = new HashMap<Integer, Data>();
       dataMap.put(1, data);
@@ -75,9 +72,9 @@ public class ShardTest {
       field.set(shard, dataMap);
       shard.clearData();
       dataMap = (HashMap<Integer, Data>) field.get(shard);
-      Assert.assertEquals(0, dataMap.size());
+      assertEquals(0, dataMap.size());
     } catch (NoSuchFieldException | IllegalAccessException e) {
-      Assert.fail("Fail to modify field access.");
+      fail("Fail to modify field access.");
     }
   }
 }

singleton/pom.xml

@@ -38,10 +38,6 @@
       <artifactId>junit-jupiter-engine</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-    </dependency>
   </dependencies>
   <build>
     <plugins>

singleton/src/test/java/com/iluwatar/singleton/ThreadSafeDoubleCheckLockingTest.java

@@ -23,15 +23,17 @@
 
 package com.iluwatar.singleton;
 
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
 import java.lang.reflect.InvocationTargetException;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Date: 12/29/15 - 19:26 PM.
  *
  * @author Jeroen Meulemeester
  */
-public class ThreadSafeDoubleCheckLockingTest extends SingletonTest<ThreadSafeDoubleCheckLocking> {
+class ThreadSafeDoubleCheckLockingTest extends SingletonTest<ThreadSafeDoubleCheckLocking> {
 
   /**
    * Create a new singleton test instance using the given 'getInstance' method.
@@ -43,12 +45,12 @@ public class ThreadSafeDoubleCheckLockingTest extends SingletonTest<ThreadSafeDo
   /**
    * Test creating new instance by refection.
    */
-  @Test(expected = InvocationTargetException.class)
-  public void testCreatingNewInstanceByRefection() throws Exception {
+  @Test
+  void testCreatingNewInstanceByRefection() throws Exception {
     ThreadSafeDoubleCheckLocking.getInstance();
     var constructor = ThreadSafeDoubleCheckLocking.class.getDeclaredConstructor();
     constructor.setAccessible(true);
-    constructor.newInstance((Object[]) null);
+    assertThrows(InvocationTargetException.class, () -> constructor.newInstance((Object[]) null));
   }
 
 }

spatial-partition/src/main/java/com/iluwatar/spatialpartition/App.java

@@ -23,8 +23,8 @@
 
 package com.iluwatar.spatialpartition;
 
+import java.security.SecureRandom;
 import java.util.HashMap;
-import java.util.Random;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -112,7 +112,7 @@ public class App {
   public static void main(String[] args) {
     var bubbles1 = new HashMap<Integer, Bubble>();
     var bubbles2 = new HashMap<Integer, Bubble>();
-    var rand = new Random();
+    var rand = new SecureRandom();
     for (int i = 0; i < 10000; i++) {
       var b = new Bubble(rand.nextInt(300), rand.nextInt(300), i, rand.nextInt(2) + 1);
       bubbles1.put(i, b);

spatial-partition/src/main/java/com/iluwatar/spatialpartition/Bubble.java

@@ -23,9 +23,9 @@
 
 package com.iluwatar.spatialpartition;
 
+import java.security.SecureRandom;
 import java.util.Collection;
 import java.util.HashMap;
-import java.util.Random;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -36,7 +36,7 @@ import org.slf4j.LoggerFactory;
 
 public class Bubble extends Point<Bubble> {
   private static final Logger LOGGER = LoggerFactory.getLogger(Bubble.class);
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
 
   final int radius;
 

subclass-sandbox/pom.xml

@@ -36,10 +36,6 @@
     <artifactId>subclass-sandbox</artifactId>
 
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-        </dependency>
         <dependency>
             <groupId>com.github.stefanbirkner</groupId>
             <artifactId>system-lambda</artifactId>

subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/AppTest.java

@@ -23,17 +23,17 @@
 
 package com.iluwatar.subclasssandbox;
 
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * App unit tests.
  */
-public class AppTest {
+class AppTest {
 
   @Test
-  public void shouldExecuteWithoutException() {
+  void shouldExecuteWithoutException() {
     assertDoesNotThrow(() -> App.main(new String[]{}));
   }
 }

subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/GroundDiveTest.java

@@ -23,45 +23,45 @@
 
 package com.iluwatar.subclasssandbox;
 
-import com.github.stefanbirkner.systemlambda.Statement;
-import org.junit.Assert;
-import org.junit.Test;
-
 import static com.github.stefanbirkner.systemlambda.SystemLambda.tapSystemOutNormalized;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.github.stefanbirkner.systemlambda.Statement;
+import org.junit.jupiter.api.Test;
 
 /**
  * GroundDive unit tests.
  */
-public class GroundDiveTest {
+class GroundDiveTest {
 
   @Test
-  public void testMove() throws Exception {
+  void testMove() throws Exception {
     var groundDive = new GroundDive();
     groundDive.move(1.0, 1.0, 1.0);
     var outputLog = getLogContent(() -> groundDive.move(1.0, 1.0, 1.0));
     var expectedLog = "Move to ( 1.0, 1.0, 1.0 )";
-    Assert.assertEquals(outputLog, expectedLog);
+    assertEquals(outputLog, expectedLog);
   }
 
   @Test
-  public void testPlaySound() throws Exception {
+  void testPlaySound() throws Exception {
     var groundDive = new GroundDive();
     var outputLog = getLogContent(() -> groundDive.playSound("SOUND_NAME", 1));
     var expectedLog = "Play SOUND_NAME with volumn 1";
-    Assert.assertEquals(outputLog, expectedLog);
+    assertEquals(outputLog, expectedLog);
   }
 
   @Test
-  public void testSpawnParticles() throws Exception {
+  void testSpawnParticles() throws Exception {
     var groundDive = new GroundDive();
     final var outputLog = getLogContent(
             () -> groundDive.spawnParticles("PARTICLE_TYPE", 100));
     final var expectedLog = "Spawn 100 particle with type PARTICLE_TYPE";
-    Assert.assertEquals(outputLog, expectedLog);
+    assertEquals(outputLog, expectedLog);
   }
 
   @Test
-  public void testActivate() throws Exception {
+  void testActivate() throws Exception {
     var groundDive = new GroundDive();
     var logs = tapSystemOutNormalized(groundDive::activate)
             .split("\n");
@@ -72,10 +72,10 @@ public class GroundDiveTest {
     final var expectedLog2 = "Play GROUNDDIVE_SOUND with volumn 5";
     final var log3 = getLogContent(logs[2]);
     final var expectedLog3 = "Spawn 20 particle with type GROUNDDIVE_PARTICLE";
-    Assert.assertEquals(logs.length, expectedSize);
-    Assert.assertEquals(log1, expectedLog1);
-    Assert.assertEquals(log2, expectedLog2);
-    Assert.assertEquals(log3, expectedLog3);
+    assertEquals(logs.length, expectedSize);
+    assertEquals(log1, expectedLog1);
+    assertEquals(log2, expectedLog2);
+    assertEquals(log3, expectedLog3);
   }
 
   private String getLogContent(Statement statement) throws Exception {

subclass-sandbox/src/test/java/com/iluwatar/subclasssandbox/SkyLaunchTest.java

@@ -23,44 +23,44 @@
 
 package com.iluwatar.subclasssandbox;
 
-import com.github.stefanbirkner.systemlambda.Statement;
-import org.junit.Assert;
-import org.junit.Test;
-
 import static com.github.stefanbirkner.systemlambda.SystemLambda.tapSystemOutNormalized;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.github.stefanbirkner.systemlambda.Statement;
+import org.junit.jupiter.api.Test;
 
 /**
  * SkyLaunch unit tests.
  */
-public class SkyLaunchTest {
+class SkyLaunchTest {
 
   @Test
-  public void testMove() throws Exception {
+  void testMove() throws Exception {
     var skyLaunch = new SkyLaunch();
     var outputLog = getLogContent(() -> skyLaunch.move(1.0, 1.0, 1.0));
     var expectedLog = "Move to ( 1.0, 1.0, 1.0 )";
-    Assert.assertEquals(outputLog, expectedLog);
+    assertEquals(outputLog, expectedLog);
   }
 
   @Test
-  public void testPlaySound() throws Exception {
+  void testPlaySound() throws Exception {
     var skyLaunch = new SkyLaunch();
     var outputLog = getLogContent(() -> skyLaunch.playSound("SOUND_NAME", 1));
     var expectedLog = "Play SOUND_NAME with volumn 1";
-    Assert.assertEquals(outputLog, expectedLog);
+    assertEquals(outputLog, expectedLog);
   }
 
   @Test
-  public void testSpawnParticles() throws Exception {
+  void testSpawnParticles() throws Exception {
     var skyLaunch = new SkyLaunch();
     var outputLog = getLogContent(
             () -> skyLaunch.spawnParticles("PARTICLE_TYPE", 100));
     var expectedLog = "Spawn 100 particle with type PARTICLE_TYPE";
-    Assert.assertEquals(outputLog, expectedLog);
+    assertEquals(outputLog, expectedLog);
   }
 
   @Test
-  public void testActivate() throws Exception {
+  void testActivate() throws Exception {
     var skyLaunch = new SkyLaunch();
     var logs = tapSystemOutNormalized(skyLaunch::activate)
             .split("\n");
@@ -71,10 +71,10 @@ public class SkyLaunchTest {
     final var expectedLog2 = "Play SKYLAUNCH_SOUND with volumn 1";
     final var log3 = getLogContent(logs[2]);
     final var expectedLog3 = "Spawn 100 particle with type SKYLAUNCH_PARTICLE";
-    Assert.assertEquals(logs.length, expectedSize);
-    Assert.assertEquals(log1, expectedLog1);
-    Assert.assertEquals(log2, expectedLog2);
-    Assert.assertEquals(log3, expectedLog3);
+    assertEquals(logs.length, expectedSize);
+    assertEquals(log1, expectedLog1);
+    assertEquals(log2, expectedLog2);
+    assertEquals(log3, expectedLog3);
   }
 
   private String getLogContent(Statement statement) throws Exception {

tolerant-reader/pom.xml

@@ -38,11 +38,6 @@
       <artifactId>junit-jupiter-engine</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.junit.jupiter</groupId>
-      <artifactId>junit-jupiter-migrationsupport</artifactId>
-      <scope>test</scope>
-    </dependency>
   </dependencies>
   <build>
     <plugins>

tolerant-reader/src/main/java/com/iluwatar/tolerantreader/RainbowFishSerializer.java

@@ -68,7 +68,7 @@ public final class RainbowFishSerializer {
     var map = Map.of(
         "name", rainbowFish.getName(),
         "age", String.format("%d", rainbowFish.getAge()),
-            "lengthMeters", String.format("%d", rainbowFish.getLengthMeters()),
+            LENGTH_METERS, String.format("%d", rainbowFish.getLengthMeters()),
             WEIGHT_TONS, String.format("%d", rainbowFish.getWeightTons()),
         "angry", Boolean.toString(rainbowFish.getAngry()),
         "hungry", Boolean.toString(rainbowFish.getHungry()),
@@ -95,7 +95,7 @@ public final class RainbowFishSerializer {
     return new RainbowFish(
         map.get("name"),
         Integer.parseInt(map.get("age")),
-        Integer.parseInt(map.get("lengthMeters")),
+        Integer.parseInt(map.get(LENGTH_METERS)),
         Integer.parseInt(map.get(WEIGHT_TONS))
     );
   }

tolerant-reader/src/test/java/com/iluwatar/tolerantreader/AppTest.java

@@ -23,14 +23,13 @@
 
 package com.iluwatar.tolerantreader;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
 import java.io.File;
-import java.io.IOException;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
-
 /**
  * Application test
  */

tolerant-reader/src/test/java/com/iluwatar/tolerantreader/RainbowFishSerializerTest.java

@@ -25,26 +25,32 @@ package com.iluwatar.tolerantreader;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import java.io.File;
-import org.junit.Rule;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.migrationsupport.rules.EnableRuleMigrationSupport;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.io.TempDir;
 
 /**
  * Date: 12/30/15 - 18:39 PM
  *
  * @author Jeroen Meulemeester
  */
-@EnableRuleMigrationSupport
-public class RainbowFishSerializerTest {
+
+class RainbowFishSerializerTest {
 
   /**
    * Create a temporary folder, used to generate files in during this test
    */
-  @Rule
-  public final TemporaryFolder testFolder = new TemporaryFolder();
+  @TempDir
+  static Path testFolder;
+
+  @BeforeEach
+  void beforeEach() {
+    assertTrue(Files.isDirectory(testFolder));
+  }
 
   /**
    * Rainbow fish version 1 used during the tests
@@ -60,11 +66,11 @@ public class RainbowFishSerializerTest {
    * Verify if a fish, written as version 1 can be read back as version 1
    */
   @Test
-  public void testWriteV1ReadV1() throws Exception {
-    final var outputFile = this.testFolder.newFile();
-    RainbowFishSerializer.writeV1(V1, outputFile.getPath());
+  void testWriteV1ReadV1() throws Exception {
+    final var outputPath = Files.createFile(testFolder.resolve("outputFile"));
+    RainbowFishSerializer.writeV1(V1, outputPath.toString());
 
-    final var fish = RainbowFishSerializer.readV1(outputFile.getPath());
+    final var fish = RainbowFishSerializer.readV1(outputPath.toString());
     assertNotSame(V1, fish);
     assertEquals(V1.getName(), fish.getName());
     assertEquals(V1.getAge(), fish.getAge());
@@ -77,11 +83,11 @@ public class RainbowFishSerializerTest {
    * Verify if a fish, written as version 2 can be read back as version 1
    */
   @Test
-  public void testWriteV2ReadV1() throws Exception {
-    final var outputFile = this.testFolder.newFile();
-    RainbowFishSerializer.writeV2(V2, outputFile.getPath());
+  void testWriteV2ReadV1() throws Exception {
+    final var outputPath = Files.createFile(testFolder.resolve("outputFile2"));
+    RainbowFishSerializer.writeV2(V2, outputPath.toString());
 
-    final var fish = RainbowFishSerializer.readV1(outputFile.getPath());
+    final var fish = RainbowFishSerializer.readV1(outputPath.toString());
     assertNotSame(V2, fish);
     assertEquals(V2.getName(), fish.getName());
     assertEquals(V2.getAge(), fish.getAge());
@@ -89,4 +95,4 @@ public class RainbowFishSerializerTest {
     assertEquals(V2.getWeightTons(), fish.getWeightTons());
   }
 
-}
+}

tolerant-reader/src/test/java/com/iluwatar/tolerantreader/RainbowFishTest.java

@@ -23,22 +23,22 @@
 
 package com.iluwatar.tolerantreader;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Date: 12/30/15 - 18:34 PM
  *
  * @author Jeroen Meulemeester
  */
-public class RainbowFishTest {
+class RainbowFishTest {
 
   /**
    * Verify if the getters of a {@link RainbowFish} return the expected values
    */
   @Test
-  public void testValues() {
+  void testValues() {
     final var fish = new RainbowFish("name", 1, 2, 3);
     assertEquals("name", fish.getName());
     assertEquals(1, fish.getAge());

tolerant-reader/src/test/java/com/iluwatar/tolerantreader/RainbowFishV2Test.java

@@ -27,20 +27,20 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Date: 12/30/15 - 18:35 PM
  *
  * @author Jeroen Meulemeester
  */
-public class RainbowFishV2Test {
+class RainbowFishV2Test {
 
   /**
    * Verify if the getters of a {@link RainbowFish} return the expected values
    */
   @Test
-  public void testValues() {
+  void testValues() {
     final var fish = new RainbowFishV2("name", 1, 2, 3, false, true, false);
     assertEquals("name", fish.getName());
     assertEquals(1, fish.getAge());

tr/singleton/README.md

@@ -0,0 +1,87 @@
+---
+layout: pattern
+title: Singleton
+folder: singleton
+permalink: /patterns/singleton/
+categories: Creational
+tags:
+- Gang of Four
+---
+
+## Amaç
+
+Bir sınıfın yalnızca bir örneğine sahip olduğundan emin olun ve ona global bir erişim noktası sağlayın.
+
+
+## Açıklama
+
+Örnek
+
+> Büyücülerin büyülerini çalıstıkları tek bir fildişi kule olabilir. Aynı büyülü fildişi kule,
+> büyücüler tarafından her zaman kullanılır. Buradaki fildişi kulesi singleton tasarım desenine örnektir.
+Özetle
+
+> Belirli bir sınıftan yalnızca bir nesnenin oluşturulmasını sağlar.
+Wikipedia açıklaması
+
+
+
+> Yazılım mühendisliğinde, tekil desen, bir sınıfın somutlaştırılmasını tek bir nesneyle sınırlayan
+> bir yazılım tasarım modelidir.Bu,sistemdeki eylemleri koordine etmek için
+> tam olarak bir nesne gerektiğinde kullanışlıdır.
+**Örnek**
+
+Joshua Bloch, Effective Java 2nd Edition p.18
+
+> Enum singleton tasarım desenini uygulamak için en iyi yoldur.
+```java
+public enum EnumIvoryTower {
+  INSTANCE
+}
+```
+
+Tanımladıktan sonra kullanmak için:
+
+```java
+var enumIvoryTower1 = EnumIvoryTower.INSTANCE;
+var enumIvoryTower2 = EnumIvoryTower.INSTANCE;
+assertEquals(enumIvoryTower1, enumIvoryTower2); // true
+```
+
+## Sınıf diagramı
+
+![alt text](https://github.com/iluwatar/java-design-patterns/blob/master/singleton/etc/singleton.urm.png)
+
+## Uygulanabilirlik
+
+Singleton tasarım deseni şu durumlarda kullanılmalıdır
+
+* Bir sınıfın tam olarak bir örneği olmalı ve iyi bilinen bir erişim noktasından istemciler tarafından erişilebilir olmalıdır.
+* Tek örnek alt sınıflandırma yoluyla genişletilebilir olduğunda ve istemciler, kodlarını değiştirmeden genişletilmiş bir örnek kullanabilmelidir
+
+## Use Case
+
+* Logging sınıflarında
+* Database bağlantılarını yönetmek için
+* File manager
+
+## Gerçek dünya örnekleri
+
+* [java.lang.Runtime#getRuntime()](http://docs.oracle.com/javase/8/docs/api/java/lang/Runtime.html#getRuntime%28%29)
+* [java.awt.Desktop#getDesktop()](http://docs.oracle.com/javase/8/docs/api/java/awt/Desktop.html#getDesktop--)
+* [java.lang.System#getSecurityManager()](http://docs.oracle.com/javase/8/docs/api/java/lang/System.html#getSecurityManager--)
+
+
+## Sonuçlar
+
+* Kendi yaratımını ve yaşam döngüsünü kontrol ederek Tek Sorumluluk İlkesini (SRP) ihlal ediyor.
+* Bu nesne tarafından kullanılan bir nesnenin ve kaynakların serbest bırakılmasını önleyen global bir paylaşılan örnek kullanmayı teşvik eder.
+* Birbirine sıkı bağlı kod oluşturur. Singleton tasarım deseni kullanan istemci sınıflarını test etmek zorlaşır.
+* Bir Singleton tasarım deseninden alt sınıflar oluşturmak neredeyse imkansız hale gelir.
+
+## Credits
+
+* [Design Patterns: Elements of Reusable Object-Oriented Software](https://www.amazon.com/gp/product/0201633612/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0201633612&linkCode=as2&tag=javadesignpat-20&linkId=675d49790ce11db99d90bde47f1aeb59)
+* [Effective Java](https://www.amazon.com/gp/product/0134685997/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0134685997&linkCode=as2&tag=javadesignpat-20&linkId=4e349f4b3ff8c50123f8147c828e53eb)
+* [Head First Design Patterns: A Brain-Friendly Guide](https://www.amazon.com/gp/product/0596007124/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0596007124&linkCode=as2&tag=javadesignpat-20&linkId=6b8b6eea86021af6c8e3cd3fc382cb5b)
+* [Refactoring to Patterns](https://www.amazon.com/gp/product/0321213351/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0321213351&linkCode=as2&tag=javadesignpat-20&linkId=2a76fcb387234bc71b1c61150b3cc3a7)

trampoline/src/main/java/com/iluwatar/trampoline/Trampoline.java

@@ -98,7 +98,7 @@ public interface Trampoline<T> {
         return trampoline(this);
       }
 
-      private T trampoline(final Trampoline<T> trampoline) {
+      T trampoline(final Trampoline<T> trampoline) {
         return Stream.iterate(trampoline, Trampoline::jump)
             .filter(Trampoline::complete)
             .findFirst()

typeobjectpattern/src/main/java/com/iluwatar/typeobject/CellPool.java

@@ -26,9 +26,9 @@ package com.iluwatar.typeobject;
 import com.iluwatar.typeobject.Candy.Type;
 
 import java.io.IOException;
+import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Random;
 import org.json.simple.parser.ParseException;
 
 /**
@@ -38,7 +38,7 @@ import org.json.simple.parser.ParseException;
  */
 
 public class CellPool {
-  private static final Random RANDOM = new Random();
+  private static final SecureRandom RANDOM = new SecureRandom();
   public static final String FRUIT = "fruit";
   public static final String CANDY = "candy";
   List<Cell> pool;

unit-of-work/pom.xml

@@ -35,19 +35,9 @@
 
     <artifactId>unit-of-work</artifactId>
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>org.junit.vintage</groupId>
-            <artifactId>junit-vintage-engine</artifactId>
-            <scope>test</scope>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>
-            <version>5.0.0</version>
             <scope>test</scope>
         </dependency>
         <dependency>

unit-of-work/src/test/java/com/iluwatar/unitofwork/AppTest.java

@@ -23,17 +23,17 @@
 
 package com.iluwatar.unitofwork;
 
-import org.junit.Test;
-
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * AppTest
  */
-public class AppTest {
+class AppTest {
 
   @Test
-  public void shouldExecuteWithoutException() {
+  void shouldExecuteWithoutException() {
     assertDoesNotThrow(() -> App.main(new String[]{}));
   }
 }

unit-of-work/src/test/java/com/iluwatar/unitofwork/StudentRepositoryTest.java

@@ -23,43 +23,32 @@
 
 package com.iluwatar.unitofwork;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
-import static org.mockito.Mockito.verifyZeroInteractions;
 
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.Mock;
-import org.mockito.runners.MockitoJUnitRunner;
+import org.junit.jupiter.api.Test;
 
 /**
  * tests {@link StudentRepository}
  */
-@RunWith(MockitoJUnitRunner.class)
-public class StudentRepositoryTest {
+
+class StudentRepositoryTest {
   private final Student student1 = new Student(1, "Ram", "street 9, cupertino");
   private final Student student2 = new Student(1, "Sham", "Z bridge, pune");
 
-  private Map<String, List<Student>> context;
-  @Mock
-  private StudentDatabase studentDatabase;
-  private StudentRepository studentRepository;
-
-  @Before
-  public void setUp() {
-    context = new HashMap<>();
-    studentRepository = new StudentRepository(context, studentDatabase);
-  }
+  private final Map<String, List<Student>> context = new HashMap<>();
+  private final StudentDatabase studentDatabase = mock(StudentDatabase.class);
+  private final StudentRepository studentRepository = new StudentRepository(context, studentDatabase);;
 
   @Test
-  public void shouldSaveNewStudentWithoutWritingToDb() {
+  void shouldSaveNewStudentWithoutWritingToDb() {
     studentRepository.registerNew(student1);
     studentRepository.registerNew(student2);
 
@@ -68,7 +57,7 @@ public class StudentRepositoryTest {
   }
 
   @Test
-  public void shouldSaveDeletedStudentWithoutWritingToDb() {
+  void shouldSaveDeletedStudentWithoutWritingToDb() {
     studentRepository.registerDeleted(student1);
     studentRepository.registerDeleted(student2);
 
@@ -77,7 +66,7 @@ public class StudentRepositoryTest {
   }
 
   @Test
-  public void shouldSaveModifiedStudentWithoutWritingToDb() {
+  void shouldSaveModifiedStudentWithoutWritingToDb() {
     studentRepository.registerModified(student1);
     studentRepository.registerModified(student2);
 
@@ -86,7 +75,7 @@ public class StudentRepositoryTest {
   }
 
   @Test
-  public void shouldSaveAllLocalChangesToDb() {
+  void shouldSaveAllLocalChangesToDb() {
     context.put(UnitActions.INSERT.getActionValue(), List.of(student1));
     context.put(UnitActions.MODIFY.getActionValue(), List.of(student1));
     context.put(UnitActions.DELETE.getActionValue(), List.of(student1));
@@ -99,7 +88,7 @@ public class StudentRepositoryTest {
   }
 
   @Test
-  public void shouldNotWriteToDbIfContextIsNull() {
+  void shouldNotWriteToDbIfContextIsNull() {
     var studentRepository = new StudentRepository(null, studentDatabase);
 
     studentRepository.commit();
@@ -108,16 +97,16 @@ public class StudentRepositoryTest {
   }
 
   @Test
-  public void shouldNotWriteToDbIfNothingToCommit() {
+  void shouldNotWriteToDbIfNothingToCommit() {
     var studentRepository = new StudentRepository(new HashMap<>(), studentDatabase);
 
     studentRepository.commit();
 
-    verifyZeroInteractions(studentDatabase);
+    verifyNoMoreInteractions(studentDatabase);
   }
 
   @Test
-  public void shouldNotInsertToDbIfNoRegisteredStudentsToBeCommitted() {
+  void shouldNotInsertToDbIfNoRegisteredStudentsToBeCommitted() {
     context.put(UnitActions.MODIFY.getActionValue(), List.of(student1));
     context.put(UnitActions.DELETE.getActionValue(), List.of(student1));
 
@@ -127,7 +116,7 @@ public class StudentRepositoryTest {
   }
 
   @Test
-  public void shouldNotModifyToDbIfNotRegisteredStudentsToBeCommitted() {
+  void shouldNotModifyToDbIfNotRegisteredStudentsToBeCommitted() {
     context.put(UnitActions.INSERT.getActionValue(), List.of(student1));
     context.put(UnitActions.DELETE.getActionValue(), List.of(student1));
 
@@ -137,7 +126,7 @@ public class StudentRepositoryTest {
   }
 
   @Test
-  public void shouldNotDeleteFromDbIfNotRegisteredStudentsToBeCommitted() {
+  void shouldNotDeleteFromDbIfNotRegisteredStudentsToBeCommitted() {
     context.put(UnitActions.INSERT.getActionValue(), List.of(student1));
     context.put(UnitActions.MODIFY.getActionValue(), List.of(student1));
 
@@ -145,4 +134,4 @@ public class StudentRepositoryTest {
 
     verify(studentDatabase, never()).delete(student1);
   }
-}
+}

update-method/pom.xml

@@ -35,10 +35,6 @@
 
     <artifactId>update-method</artifactId>
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>

update-method/src/main/java/com/iluwatar/updatemethod/World.java

@@ -23,9 +23,9 @@
 
 package com.iluwatar.updatemethod;
 
+import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Random;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -66,7 +66,7 @@ public class World {
    */
   private void processInput() {
     try {
-      int lag = new Random().nextInt(200) + 50;
+      int lag = new SecureRandom().nextInt(200) + 50;
       Thread.sleep(lag);
     } catch (InterruptedException e) {
       LOGGER.error(e.getMessage());

update-method/src/test/java/com/iluwatar/updatemethod/AppTest.java

@@ -23,14 +23,14 @@
 
 package com.iluwatar.updatemethod;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 
-public class AppTest {
+class AppTest {
 
   @Test
-  public void shouldExecuteApplicationWithoutException() {
+  void shouldExecuteApplicationWithoutException() {
     assertDoesNotThrow(() -> App.main(new String[]{}));
   }
 }

update-method/src/test/java/com/iluwatar/updatemethod/SkeletonTest.java

@@ -23,56 +23,60 @@
 
 package com.iluwatar.updatemethod;
 
-import org.junit.After;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
 
-public class SkeletonTest {
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-  private Skeleton skeleton;
 
-  @Before
-  public void setup() {
+class SkeletonTest {
+
+  private static Skeleton skeleton;
+
+  @BeforeAll
+  public static void setup() {
     skeleton = new Skeleton(1);
   }
 
-  @After
-  public void tearDown() {
+  @AfterAll
+  public static void tearDown() {
     skeleton = null;
   }
 
   @Test
-  public void testUpdateForPatrollingLeft() {
+  void testUpdateForPatrollingLeft() {
     skeleton.patrollingLeft = true;
     skeleton.setPosition(50);
     skeleton.update();
-    Assert.assertEquals(49, skeleton.getPosition());
+    assertEquals(49, skeleton.getPosition());
   }
 
   @Test
-  public void testUpdateForPatrollingRight() {
+  void testUpdateForPatrollingRight() {
     skeleton.patrollingLeft = false;
     skeleton.setPosition(50);
     skeleton.update();
-    Assert.assertEquals(51, skeleton.getPosition());
+    assertEquals(51, skeleton.getPosition());
   }
 
   @Test
-  public void testUpdateForReverseDirectionFromLeftToRight() {
+  void testUpdateForReverseDirectionFromLeftToRight() {
     skeleton.patrollingLeft = true;
     skeleton.setPosition(1);
     skeleton.update();
-    Assert.assertEquals(0, skeleton.getPosition());
-    Assert.assertEquals(false, skeleton.patrollingLeft);
+    assertEquals(0, skeleton.getPosition());
+    assertFalse(skeleton.patrollingLeft);
   }
 
   @Test
-  public void testUpdateForReverseDirectionFromRightToLeft() {
+  void testUpdateForReverseDirectionFromRightToLeft() {
     skeleton.patrollingLeft = false;
     skeleton.setPosition(99);
     skeleton.update();
-    Assert.assertEquals(100, skeleton.getPosition());
-    Assert.assertEquals(true, skeleton.patrollingLeft);
+    assertEquals(100, skeleton.getPosition());
+    assertTrue(skeleton.patrollingLeft);
   }
 }

update-method/src/test/java/com/iluwatar/updatemethod/StatueTest.java

@@ -23,36 +23,37 @@
 
 package com.iluwatar.updatemethod;
 
-import org.junit.After;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
 
-public class StatueTest {
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
-  private Statue statue;
+class StatueTest {
 
-  @Before
-  public void setup() {
+  private static Statue statue;
+
+  @BeforeAll
+  public static void setup() {
     statue = new Statue(1, 20);
   }
 
-  @After
-  public void tearDown() {
+  @AfterAll
+  public static void tearDown() {
     statue = null;
   }
 
   @Test
-  public void testUpdateForPendingShoot() {
+  void testUpdateForPendingShoot() {
     statue.frames = 10;
     statue.update();
-    Assert.assertEquals(11, statue.frames);
+    assertEquals(11, statue.frames);
   }
 
   @Test
-  public void testUpdateForShooting() {
+  void testUpdateForShooting() {
     statue.frames = 19;
     statue.update();
-    Assert.assertEquals(0, statue.frames);
+    assertEquals(0, statue.frames);
   }
 }

update-method/src/test/java/com/iluwatar/updatemethod/WorldTest.java

@@ -23,41 +23,44 @@
 
 package com.iluwatar.updatemethod;
 
-import org.junit.After;
-import org.junit.Assert;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
 
-public class WorldTest {
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
-  private World world;
+class WorldTest {
 
-  @Before
-  public void setup() {
+  private static World world;
+
+  @BeforeAll
+  public static void setup() {
     world = new World();
   }
 
-  @After
-  public void tearDown() {
+  @AfterAll
+  public static void tearDown() {
     world = null;
   }
 
   @Test
-  public void testRun() {
+  void testRun() {
     world.run();
-    Assert.assertEquals(true, world.isRunning);
+    assertTrue(world.isRunning);
   }
 
   @Test
-  public void testStop() {
+  void testStop() {
     world.stop();
-    Assert.assertEquals(false, world.isRunning);
+    assertFalse(world.isRunning);
   }
 
   @Test
-  public void testAddEntity() {
+  void testAddEntity() {
     var entity = new Skeleton(1);
     world.addEntity(entity);
-    Assert.assertEquals(entity, world.entities.get(0));
+    assertEquals(entity, world.entities.get(0));
   }
 }