1) Refactored LotteryNumbers to use Joiner from guava library to join lottery numbers. 2) Solved potential thread safety issue in LotteryTicketId class, where it was using raw primitive value and incrementing it which is not thread-safe. So used AtomicInteger for brevity 3) assertEquals arguments were in incorrect order at many places, so changed order of those 4) Replaced assertFalse and assertTrue at some places with assertEquals and assertNotEquals for reducing complexity of code 5) Removed public modifiers from test cases, as they are no more needed by JUnit 5

hexagonal/src/main/java/com/iluwatar/hexagonal/database/MongoTicketRepository.java

@@ -110,21 +110,6 @@ public class MongoTicketRepository implements LotteryTicketRepository {
     return result.getInteger("seq");
   }
 
-  /**
-   * @return mongo client
-   */
-  public MongoClient getMongoClient() {
-    return mongoClient;
-  }
-
-  /**
-   *
-   * @return mongo database
-   */
-  public MongoDatabase getMongoDatabase() {
-    return database;
-  }
-
   /**
    *
    * @return tickets collection

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

@@ -22,6 +22,8 @@
  */
 package com.iluwatar.hexagonal.domain;
 
+import com.google.common.base.Joiner;
+
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.PrimitiveIterator;
@@ -84,15 +86,7 @@ public class LotteryNumbers {
    * @return numbers as comma separated string
    */
   public String getNumbersAsString() {
-    StringBuilder builder = new StringBuilder();
-    Iterator<Integer> iterator = numbers.iterator();
-    for (int i = 0; i < NUM_NUMBERS; i++) {
-      builder.append(iterator.next());
-      if (i < NUM_NUMBERS - 1) {
-        builder.append(",");
-      }
-    }
-    return builder.toString();
+    return Joiner.on(',').join(numbers);
   }
   
   /**

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

@@ -22,17 +22,19 @@
  */
 package com.iluwatar.hexagonal.domain;
 
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.LongAdder;
+
 /**
  * Lottery ticked id
  */
 public class LotteryTicketId {
 
-  private static volatile int numAllocated;
+  private static AtomicInteger numAllocated = new AtomicInteger(0);
   private final int id;
   
   public LotteryTicketId() {
-    this.id = numAllocated + 1;
-    numAllocated++;
+    this.id = numAllocated.incrementAndGet();
   }
 
   public LotteryTicketId(int id) {

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

@@ -27,10 +27,10 @@ import org.junit.jupiter.api.Test;
 /**
  * Unit test for simple App.
  */
-public class AppTest {
+class AppTest {
 
   @Test
-  public void testApp() {
+  void testApp() {
     String[] args = {};
     App.main(args);
   }

hexagonal/src/test/java/com/iluwatar/hexagonal/banking/InMemoryBankTest.java

@@ -32,19 +32,19 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * Tests for banking
  *
  */
-public class InMemoryBankTest {
+class InMemoryBankTest {
 
   private final WireTransfers bank = new InMemoryBank();
   
   @Test
-  public void testInit() {
-    assertEquals(bank.getFunds("foo"), 0);
+  void testInit() {
+    assertEquals(0, bank.getFunds("foo"));
     bank.setFunds("foo", 100);
-    assertEquals(bank.getFunds("foo"), 100);
+    assertEquals(100, bank.getFunds("foo"));
     bank.setFunds("bar", 150);
-    assertEquals(bank.getFunds("bar"), 150);
+    assertEquals(150, bank.getFunds("bar"));
     assertTrue(bank.transferFunds(50, "bar", "foo"));
-    assertEquals(bank.getFunds("foo"), 150);
-    assertEquals(bank.getFunds("bar"), 100);
+    assertEquals(150, bank.getFunds("foo"));
+    assertEquals(100, bank.getFunds("bar"));
   }
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/banking/MongoBankTest.java

@@ -34,7 +34,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
  * Tests for Mongo banking adapter
  */
 @Disabled
-public class MongoBankTest {
+class MongoBankTest {
 
   private static final String TEST_DB = "lotteryDBTest";
   private static final String TEST_ACCOUNTS_COLLECTION = "testAccounts";
@@ -42,7 +42,7 @@ public class MongoBankTest {
   private MongoBank mongoBank;
 
   @BeforeEach
-  public void init() {
+  void init() {
     MongoConnectionPropertiesLoader.load();
     MongoClient mongoClient = new MongoClient(System.getProperty("mongo-host"),
         Integer.parseInt(System.getProperty("mongo-port")));
@@ -52,12 +52,12 @@ public class MongoBankTest {
   }
 
   @Test
-  public void testSetup() {
+  void testSetup() {
     assertEquals(0, mongoBank.getAccountsCollection().count());
   }
 
   @Test
-  public void testFundTransfers() {
+  void testFundTransfers() {
     assertEquals(0, mongoBank.getFunds("000-000"));
     mongoBank.setFunds("000-000", 10);
     assertEquals(10, mongoBank.getFunds("000-000"));

hexagonal/src/test/java/com/iluwatar/hexagonal/database/InMemoryTicketRepositoryTest.java

@@ -38,23 +38,23 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * Tests for {@link LotteryTicketRepository}
  *
  */
-public class InMemoryTicketRepositoryTest {
+class InMemoryTicketRepositoryTest {
 
   private final LotteryTicketRepository repository = new InMemoryTicketRepository();
   
   @BeforeEach
-  public void clear() {
+  void clear() {
     repository.deleteAll();
   }
   
   @Test
-  public void testCrudOperations() {
+  void testCrudOperations() {
     LotteryTicketRepository repository = new InMemoryTicketRepository();
-    assertEquals(repository.findAll().size(), 0);
+    assertTrue(repository.findAll().isEmpty());
     LotteryTicket ticket = LotteryTestUtils.createLotteryTicket();
     Optional<LotteryTicketId> id = repository.save(ticket);
     assertTrue(id.isPresent());
-    assertEquals(repository.findAll().size(), 1);
+    assertEquals(1, repository.findAll().size());
     Optional<LotteryTicket> optionalTicket = repository.findById(id.get());
     assertTrue(optionalTicket.isPresent());
   }

hexagonal/src/test/java/com/iluwatar/hexagonal/database/MongoTicketRepositoryTest.java

@@ -41,7 +41,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * Tests for Mongo based ticket repository
  */
 @Disabled
-public class MongoTicketRepositoryTest {
+class MongoTicketRepositoryTest {
 
   private static final String TEST_DB = "lotteryTestDB";
   private static final String TEST_TICKETS_COLLECTION = "lotteryTestTickets";
@@ -50,7 +50,7 @@ public class MongoTicketRepositoryTest {
   private MongoTicketRepository repository;
 
   @BeforeEach
-  public void init() {
+  void init() {
     MongoConnectionPropertiesLoader.load();
     MongoClient mongoClient = new MongoClient(System.getProperty("mongo-host"),
         Integer.parseInt(System.getProperty("mongo-port")));
@@ -61,20 +61,20 @@ public class MongoTicketRepositoryTest {
   }
 
   @Test
-  public void testSetup() {
-    assertTrue(repository.getCountersCollection().count() == 1);
-    assertTrue(repository.getTicketsCollection().count() == 0);
+  void testSetup() {
+    assertEquals(1, repository.getCountersCollection().count());
+    assertEquals(0, repository.getTicketsCollection().count());
   }
 
   @Test
-  public void testNextId() {
+  void testNextId() {
     assertEquals(1, repository.getNextId());
     assertEquals(2, repository.getNextId());
     assertEquals(3, repository.getNextId());
   }
 
   @Test
-  public void testCrudOperations() {
+  void testCrudOperations() {
     // create new lottery ticket and save it
     PlayerDetails details = new PlayerDetails("foo@bar.com", "123-123", "07001234");
     LotteryNumbers random = LotteryNumbers.createRandom();

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryNumbersTest.java

@@ -28,7 +28,7 @@ import java.util.Arrays;
 import java.util.HashSet;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -37,10 +37,10 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * Unit tests for {@link LotteryNumbers}
  *
  */
-public class LotteryNumbersTest {
+class LotteryNumbersTest {
   
   @Test
-  public void testGivenNumbers() {
+  void testGivenNumbers() {
     LotteryNumbers numbers = LotteryNumbers.create(
             new HashSet<>(Arrays.asList(1, 2, 3, 4)));
     assertEquals(numbers.getNumbers().size(), 4);
@@ -51,7 +51,7 @@ public class LotteryNumbersTest {
   }
   
   @Test
-  public void testNumbersCantBeModified() {
+  void testNumbersCantBeModified() {
     LotteryNumbers numbers = LotteryNumbers.create(
             new HashSet<>(Arrays.asList(1, 2, 3, 4)));
     assertThrows(UnsupportedOperationException.class, () -> {
@@ -60,20 +60,20 @@ public class LotteryNumbersTest {
   }
   
   @Test
-  public void testRandomNumbers() {
+  void testRandomNumbers() {
     LotteryNumbers numbers = LotteryNumbers.createRandom();
     assertEquals(numbers.getNumbers().size(), LotteryNumbers.NUM_NUMBERS);
   }
   
   @Test
-  public void testEquals() {
+  void testEquals() {
     LotteryNumbers numbers1 = LotteryNumbers.create(
             new HashSet<>(Arrays.asList(1, 2, 3, 4)));
     LotteryNumbers numbers2 = LotteryNumbers.create(
             new HashSet<>(Arrays.asList(1, 2, 3, 4)));
-    assertTrue(numbers1.equals(numbers2));
+    assertEquals(numbers1, numbers2);
     LotteryNumbers numbers3 = LotteryNumbers.create(
             new HashSet<>(Arrays.asList(11, 12, 13, 14)));
-    assertFalse(numbers1.equals(numbers3));
+    assertNotEquals(numbers1, numbers3);
   }
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryTest.java

@@ -38,6 +38,7 @@ import java.util.Map;
 import java.util.Optional;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
@@ -45,7 +46,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * Test the lottery system
  *
  */
-public class LotteryTest {
+class LotteryTest {
 
   private Injector injector;
   @Inject
@@ -55,22 +56,22 @@ public class LotteryTest {
   @Inject
   private WireTransfers wireTransfers;
 
-  public LotteryTest() {
+  LotteryTest() {
     this.injector = Guice.createInjector(new LotteryTestingModule());
   }
 
   @BeforeEach
-  public void setup() {
+  void setup() {
     injector.injectMembers(this);
     // add funds to the test player's bank account
     wireTransfers.setFunds("123-12312", 100);
   }
   
   @Test
-  public void testLottery() {
+  void testLottery() {
     // admin resets the lottery
     administration.resetLottery();
-    assertEquals(administration.getAllSubmittedTickets().size(), 0);
+    assertEquals(0, administration.getAllSubmittedTickets().size());
     
     // players submit the lottery tickets
     Optional<LotteryTicketId> ticket1 = service.submitTicket(LotteryTestUtils.createLotteryTicket("cvt@bbb.com",
@@ -82,7 +83,7 @@ public class LotteryTest {
     Optional<LotteryTicketId> ticket3 = service.submitTicket(LotteryTestUtils.createLotteryTicket("arg@boo.com",
         "123-12312", "+32421255", new HashSet<>(Arrays.asList(6, 8, 13, 19))));
     assertTrue(ticket3.isPresent());
-    assertEquals(administration.getAllSubmittedTickets().size(), 3);
+    assertEquals(3, administration.getAllSubmittedTickets().size());
     
     // perform lottery
     LotteryNumbers winningNumbers = administration.performLottery();
@@ -91,23 +92,23 @@ public class LotteryTest {
     Optional<LotteryTicketId> ticket4 = service.submitTicket(LotteryTestUtils.createLotteryTicket("lucky@orb.com",
         "123-12312", "+12421255", winningNumbers.getNumbers()));
     assertTrue(ticket4.isPresent());
-    assertEquals(administration.getAllSubmittedTickets().size(), 4);
+    assertEquals(4, administration.getAllSubmittedTickets().size());
     
     // check winners
     Map<LotteryTicketId, LotteryTicket> tickets = administration.getAllSubmittedTickets();
     for (LotteryTicketId id: tickets.keySet()) {
       LotteryTicketCheckResult checkResult = service.checkTicketForPrize(id, winningNumbers);
-      assertTrue(checkResult.getResult() != CheckResult.TICKET_NOT_SUBMITTED);
+      assertNotEquals(CheckResult.TICKET_NOT_SUBMITTED, checkResult.getResult());
       if (checkResult.getResult().equals(CheckResult.WIN_PRIZE)) {
         assertTrue(checkResult.getPrizeAmount() > 0);
       } else if (checkResult.getResult().equals(CheckResult.WIN_PRIZE)) {
-        assertEquals(checkResult.getPrizeAmount(), 0);
+        assertEquals(0, checkResult.getPrizeAmount());
       }
     }
     
     // check another ticket that has not been submitted
     LotteryTicketCheckResult checkResult = service.checkTicketForPrize(new LotteryTicketId(), winningNumbers);
-    assertTrue(checkResult.getResult() == CheckResult.TICKET_NOT_SUBMITTED);
-    assertEquals(checkResult.getPrizeAmount(), 0);
+    assertEquals(CheckResult.TICKET_NOT_SUBMITTED, checkResult.getResult());
+    assertEquals(0, checkResult.getPrizeAmount());
   }
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryTicketCheckResultTest.java

@@ -26,21 +26,21 @@ import com.iluwatar.hexagonal.domain.LotteryTicketCheckResult.CheckResult;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 /**
  * 
  * Unit tests for {@link LotteryTicketCheckResult}
  *
  */
-public class LotteryTicketCheckResultTest {
+class LotteryTicketCheckResultTest {
 
   @Test
-  public void testEquals() {
+  void testEquals() {
     LotteryTicketCheckResult result1 = new LotteryTicketCheckResult(CheckResult.NO_PRIZE);
     LotteryTicketCheckResult result2 = new LotteryTicketCheckResult(CheckResult.NO_PRIZE);
     assertEquals(result1, result2);
     LotteryTicketCheckResult result3 = new LotteryTicketCheckResult(CheckResult.WIN_PRIZE, 300000);
-    assertFalse(result1.equals(result3));
+    assertNotEquals(result1, result3);
   } 
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryTicketIdTest.java

@@ -24,22 +24,22 @@ package com.iluwatar.hexagonal.domain;
 
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 /**
  * Tests for lottery ticket id
  */
-public class LotteryTicketIdTest {
+class LotteryTicketIdTest {
 
   @Test
-  public void testEquals() {
+  void testEquals() {
     LotteryTicketId ticketId1 = new LotteryTicketId();
     LotteryTicketId ticketId2 = new LotteryTicketId();
     LotteryTicketId ticketId3 = new LotteryTicketId();
-    assertFalse(ticketId1.equals(ticketId2));
-    assertFalse(ticketId2.equals(ticketId3));
+    assertNotEquals(ticketId1, ticketId2);
+    assertNotEquals(ticketId2, ticketId3);
     LotteryTicketId ticketId4 = new LotteryTicketId(ticketId1.getId());
-    assertTrue(ticketId1.equals(ticketId4));
+    assertEquals(ticketId1, ticketId4);
   }
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/LotteryTicketTest.java

@@ -29,14 +29,15 @@ import java.util.HashSet;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 /**
  * Test Lottery Tickets for equality
  */
-public class LotteryTicketTest {
+class LotteryTicketTest {
 
   @Test
-  public void testEquals() {
+  void testEquals() {
     PlayerDetails details1 = new PlayerDetails("bob@foo.bar", "1212-121212", "+34332322");
     LotteryNumbers numbers1 = LotteryNumbers.create(new HashSet<Integer>(Arrays.asList(1, 2, 3, 4)));
     LotteryTicket ticket1 = new LotteryTicket(new LotteryTicketId(), details1, numbers1);
@@ -47,6 +48,6 @@ public class LotteryTicketTest {
     PlayerDetails details3 = new PlayerDetails("elsa@foo.bar", "1223-121212", "+49332322");
     LotteryNumbers numbers3 = LotteryNumbers.create(new HashSet<Integer>(Arrays.asList(1, 2, 3, 8)));
     LotteryTicket ticket3 = new LotteryTicket(new LotteryTicketId(), details3, numbers3);
-    assertFalse(ticket1.equals(ticket3));
+    assertNotEquals(ticket1, ticket3);
   }
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/domain/PlayerDetailsTest.java

@@ -25,21 +25,21 @@ package com.iluwatar.hexagonal.domain;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 /**
  * 
  * Unit tests for {@link PlayerDetails}
  *
  */
-public class PlayerDetailsTest {
+class PlayerDetailsTest {
 
   @Test
-  public void testEquals() {
+  void testEquals() {
     PlayerDetails details1 = new PlayerDetails("tom@foo.bar", "11212-123434", "+12323425");
     PlayerDetails details2 = new PlayerDetails("tom@foo.bar", "11212-123434", "+12323425");
     assertEquals(details1, details2);
     PlayerDetails details3 = new PlayerDetails("john@foo.bar", "16412-123439", "+34323432");
-    assertFalse(details1.equals(details3));
+    assertNotEquals(details1, details3);
   }  
 }

hexagonal/src/test/java/com/iluwatar/hexagonal/eventlog/MongoEventLogTest.java

@@ -35,7 +35,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
  * Tests for Mongo event log
  */
 @Disabled
-public class MongoEventLogTest {
+class MongoEventLogTest {
 
   private static final String TEST_DB = "lotteryDBTest";
   private static final String TEST_EVENTS_COLLECTION = "testEvents";
@@ -43,7 +43,7 @@ public class MongoEventLogTest {
   private MongoEventLog mongoEventLog;
 
   @BeforeEach
-  public void init() {
+  void init() {
     MongoConnectionPropertiesLoader.load();
     MongoClient mongoClient = new MongoClient(System.getProperty("mongo-host"),
         Integer.parseInt(System.getProperty("mongo-port")));
@@ -53,12 +53,12 @@ public class MongoEventLogTest {
   }
 
   @Test
-  public void testSetup() {
+  void testSetup() {
     assertEquals(0, mongoEventLog.getEventsCollection().count());
   }
 
   @Test
-  public void testFundTransfers() {
+  void testFundTransfers() {
     PlayerDetails playerDetails = new PlayerDetails("john@wayne.com", "000-000", "03432534543");
     mongoEventLog.prizeError(playerDetails, 1000);
     assertEquals(1, mongoEventLog.getEventsCollection().count());