Add proper unit tests for dependency-injection pattern

dependency-injection/src/test/java/com/iluwatar/dependency/injection/AdvancedWizardTest.java

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+package com.iluwatar.dependency.injection;
+
+import org.junit.Test;
+
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+
+/**
+ * Date: 12/10/15 - 8:40 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class AdvancedWizardTest extends StdOutTest {
+
+  /**
+   * Test if the {@link AdvancedWizard} smokes whatever instance of {@link Tobacco} is passed to him
+   * through the constructor parameter
+   */
+  @Test
+  public void testSmokeEveryThing() throws Exception {
+
+    final Tobacco[] tobaccos = {
+        new OldTobyTobacco(), new RivendellTobacco(), new SecondBreakfastTobacco()
+    };
+
+    for (final Tobacco tobacco : tobaccos) {
+      final AdvancedWizard advancedWizard = new AdvancedWizard(tobacco);
+      advancedWizard.smoke();
+
+      // Verify if the wizard is smoking the correct tobacco ...
+      verify(getStdOutMock(), times(1)).println("AdvancedWizard smoking " + tobacco.getClass().getSimpleName());
+
+      // ... and nothing else is happening.
+      verifyNoMoreInteractions(getStdOutMock());
+    }
+
+  }
+
+}

dependency-injection/src/test/java/com/iluwatar/dependency/injection/GuiceWizardTest.java

@@ -0,0 +1,78 @@
+package com.iluwatar.dependency.injection;
+
+import com.google.inject.AbstractModule;
+import com.google.inject.Guice;
+import com.google.inject.Injector;
+
+import org.junit.Test;
+
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+
+/**
+ * Date: 12/10/15 - 8:57 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class GuiceWizardTest extends StdOutTest {
+
+  /**
+   * Test if the {@link GuiceWizard} smokes whatever instance of {@link Tobacco} is passed to him
+   * through the constructor parameter
+   */
+  @Test
+  public void testSmokeEveryThingThroughConstructor() throws Exception {
+
+    final Tobacco[] tobaccos = {
+        new OldTobyTobacco(), new RivendellTobacco(), new SecondBreakfastTobacco()
+    };
+
+    for (final Tobacco tobacco : tobaccos) {
+      final GuiceWizard guiceWizard = new GuiceWizard(tobacco);
+      guiceWizard.smoke();
+
+      // Verify if the wizard is smoking the correct tobacco ...
+      verify(getStdOutMock(), times(1)).println("GuiceWizard smoking " + tobacco.getClass().getSimpleName());
+
+      // ... and nothing else is happening.
+      verifyNoMoreInteractions(getStdOutMock());
+    }
+
+  }
+
+  /**
+   * Test if the {@link GuiceWizard} smokes whatever instance of {@link Tobacco} is passed to him
+   * through the Guice google inject framework
+   */
+  @Test
+  public void testSmokeEveryThingThroughInjectionFramework() throws Exception {
+
+    @SuppressWarnings("unchecked")
+    final Class<? extends Tobacco>[] tobaccos = new Class[]{
+        OldTobyTobacco.class, RivendellTobacco.class, SecondBreakfastTobacco.class
+    };
+
+    for (final Class<? extends Tobacco> tobaccoClass : tobaccos) {
+      // Configure the tobacco in the injection framework ...
+      final Injector injector = Guice.createInjector(new AbstractModule() {
+        @Override
+        protected void configure() {
+          bind(Tobacco.class).to(tobaccoClass);
+        }
+      });
+
+      // ... and create a new wizard with it
+      final GuiceWizard guiceWizard = injector.getInstance(GuiceWizard.class);
+      guiceWizard.smoke();
+
+      // Verify if the wizard is smoking the correct tobacco ...
+      verify(getStdOutMock(), times(1)).println("GuiceWizard smoking " + tobaccoClass.getSimpleName());
+
+      // ... and nothing else is happening.
+      verifyNoMoreInteractions(getStdOutMock());
+    }
+
+  }
+
+}

dependency-injection/src/test/java/com/iluwatar/dependency/injection/SimpleWizardTest.java

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+package com.iluwatar.dependency.injection;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.PrintStream;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+
+/**
+ * Date: 12/10/15 - 8:26 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class SimpleWizardTest extends StdOutTest {
+
+  /**
+   * Test if the {@link SimpleWizard} does the only thing it can do: Smoke it's {@link
+   * OldTobyTobacco}
+   */
+  @Test
+  public void testSmoke() {
+    final SimpleWizard simpleWizard = new SimpleWizard();
+    simpleWizard.smoke();
+    verify(getStdOutMock(), times(1)).println("SimpleWizard smoking OldTobyTobacco");
+    verifyNoMoreInteractions(getStdOutMock());
+  }
+
+}

dependency-injection/src/test/java/com/iluwatar/dependency/injection/StdOutTest.java

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+package com.iluwatar.dependency.injection;
+
+import org.junit.After;
+import org.junit.Before;
+
+import java.io.PrintStream;
+
+import static org.mockito.Mockito.mock;
+
+/**
+ * Date: 12/10/15 - 8:37 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+public abstract class StdOutTest {
+
+  /**
+   * The mocked standard out {@link PrintStream}, required since the actions of the wizard don't
+   * have any influence on any other accessible objects, except for writing to std-out using {@link
+   * System#out}
+   */
+  private final PrintStream stdOutMock = mock(PrintStream.class);
+
+  /**
+   * Keep the original std-out so it can be restored after the test
+   */
+  private final PrintStream stdOutOrig = System.out;
+
+  /**
+   * Inject the mocked std-out {@link PrintStream} into the {@link System} class before each test
+   */
+  @Before
+  public void setUp() {
+    System.setOut(this.stdOutMock);
+  }
+
+  /**
+   * Removed the mocked std-out {@link PrintStream} again from the {@link System} class
+   */
+  @After
+  public void tearDown() {
+    System.setOut(this.stdOutOrig);
+  }
+
+  /**
+   * Get the mocked stdOut {@link PrintStream}
+   *
+   * @return The stdOut print stream mock, renewed before each test
+   */
+  final PrintStream getStdOutMock() {
+    return this.stdOutMock;
+  }
+}