Added tests for generic observer pattern

observer/src/main/java/com/iluwatar/observer/generic/Observable.java

@@ -22,6 +22,10 @@ public abstract class Observable<S extends Observable<S, O, A>, O extends Observ
     this.observers.add(observer);
   }
 
+  public void removeObserver(O observer) {
+    this.observers.remove(observer);
+  }
+
   /**
    * Notify observers
    */

observer/src/test/java/com/iluwatar/observer/StdOutTest.java

@@ -47,7 +47,7 @@ public abstract class StdOutTest {
    *
    * @return The stdOut print stream mock, renewed before each test
    */
-  final PrintStream getStdOutMock() {
+  protected final PrintStream getStdOutMock() {
     return this.stdOutMock;
   }
 

observer/src/test/java/com/iluwatar/observer/generic/GHobbitsTest.java

@@ -0,0 +1,41 @@
+package com.iluwatar.observer.generic;
+
+import com.iluwatar.observer.Hobbits;
+import com.iluwatar.observer.WeatherObserverTest;
+import com.iluwatar.observer.WeatherType;
+
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+/**
+ * Date: 12/27/15 - 12:07 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+@RunWith(Parameterized.class)
+public class GHobbitsTest extends ObserverTest<GHobbits> {
+
+  @Parameterized.Parameters
+  public static Collection<Object[]> data() {
+    final ArrayList<Object[]> testData = new ArrayList<>();
+    testData.add(new Object[]{WeatherType.SUNNY, "The happy hobbits bade in the warm sun."});
+    testData.add(new Object[]{WeatherType.RAINY, "The hobbits look for cover from the rain."});
+    testData.add(new Object[]{WeatherType.WINDY, "The hobbits hold their hats tightly in the windy weather."});
+    testData.add(new Object[]{WeatherType.COLD, "The hobbits are shivering in the cold weather."});
+    return testData;
+  }
+
+  /**
+   * Create a new test with the given weather and expected response
+   *
+   * @param weather  The weather that should be unleashed on the observer
+   * @param response The expected response from the observer
+   */
+  public GHobbitsTest(final WeatherType weather, final String response) {
+    super(weather, response, GHobbits::new);
+  }
+
+}

observer/src/test/java/com/iluwatar/observer/generic/GWeatherTest.java

@@ -0,0 +1,65 @@
+package com.iluwatar.observer.generic;
+
+import com.iluwatar.observer.StdOutTest;
+import com.iluwatar.observer.WeatherObserver;
+import com.iluwatar.observer.WeatherType;
+
+import org.junit.Test;
+import org.mockito.InOrder;
+
+import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.verifyZeroInteractions;
+
+/**
+ * Date: 12/27/15 - 11:08 AM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class GWeatherTest extends StdOutTest {
+
+  /**
+   * Add a {@link WeatherObserver}, verify if it gets notified of a weather change, remove the
+   * observer again and verify that there are no more notifications.
+   */
+  @Test
+  public void testAddRemoveObserver() {
+    final Race observer = mock(Race.class);
+
+    final GWeather weather = new GWeather();
+    weather.addObserver(observer);
+    verifyZeroInteractions(observer);
+
+    weather.timePasses();
+    verify(getStdOutMock()).println("The weather changed to rainy.");
+    verify(observer).update(weather, WeatherType.RAINY);
+
+    weather.removeObserver(observer);
+    weather.timePasses();
+    verify(getStdOutMock()).println("The weather changed to windy.");
+
+    verifyNoMoreInteractions(observer, getStdOutMock());
+  }
+
+  /**
+   * Verify if the weather passes in the order of the {@link WeatherType}s
+   */
+  @Test
+  public void testTimePasses() {
+    final Race observer = mock(Race.class);
+    final GWeather weather = new GWeather();
+    weather.addObserver(observer);
+
+    final InOrder inOrder = inOrder(observer, getStdOutMock());
+    final WeatherType[] weatherTypes = WeatherType.values();
+    for (int i = 1; i < 20; i++) {
+      weather.timePasses();
+      inOrder.verify(observer).update(weather, weatherTypes[i % weatherTypes.length]);
+    }
+
+    verifyNoMoreInteractions(observer);
+  }
+
+}

observer/src/test/java/com/iluwatar/observer/generic/ObserverTest.java

@@ -0,0 +1,62 @@
+package com.iluwatar.observer.generic;
+
+import com.iluwatar.observer.StdOutTest;
+import com.iluwatar.observer.WeatherType;
+
+import org.junit.Test;
+
+import java.util.function.Supplier;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.verifyZeroInteractions;
+
+/**
+ * Date: 12/27/15 - 11:44 AM
+ *
+ * @author Jeroen Meulemeester
+ */
+public abstract class ObserverTest<O extends Observer> extends StdOutTest {
+
+  /**
+   * The observer instance factory
+   */
+  private final Supplier<O> factory;
+
+  /**
+   * The weather type currently tested
+   */
+  private final WeatherType weather;
+
+  /**
+   * The expected response from the observer
+   */
+  private final String response;
+
+  /**
+   * Create a new test instance using the given parameters
+   *
+   * @param weather  The weather currently being tested
+   * @param response The expected response from the observer
+   * @param factory  The factory, used to create an instance of the tested observer
+   */
+  ObserverTest(final WeatherType weather, final String response, final Supplier<O> factory) {
+    this.weather = weather;
+    this.response = response;
+    this.factory = factory;
+  }
+
+  /**
+   * Verify if the weather has the expected influence on the observer
+   */
+  @Test
+  public void testObserver() {
+    final O observer = this.factory.get();
+    verifyZeroInteractions(getStdOutMock());
+
+    observer.update(null, this.weather);
+    verify(getStdOutMock()).println(this.response);
+    verifyNoMoreInteractions(getStdOutMock());
+  }
+
+}

observer/src/test/java/com/iluwatar/observer/generic/OrcsTest.java

@@ -0,0 +1,39 @@
+package com.iluwatar.observer.generic;
+
+import com.iluwatar.observer.WeatherType;
+
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+/**
+ * Date: 12/27/15 - 12:07 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+@RunWith(Parameterized.class)
+public class OrcsTest extends ObserverTest<GOrcs> {
+
+  @Parameterized.Parameters
+  public static Collection<Object[]> data() {
+    final ArrayList<Object[]> testData = new ArrayList<>();
+    testData.add(new Object[]{WeatherType.SUNNY, "The sun hurts the orcs' eyes."});
+    testData.add(new Object[]{WeatherType.RAINY, "The orcs are dripping wet."});
+    testData.add(new Object[]{WeatherType.WINDY, "The orc smell almost vanishes in the wind."});
+    testData.add(new Object[]{WeatherType.COLD, "The orcs are freezing cold."});
+    return testData;
+  }
+
+  /**
+   * Create a new test with the given weather and expected response
+   *
+   * @param weather  The weather that should be unleashed on the observer
+   * @param response The expected response from the observer
+   */
+  public OrcsTest(final WeatherType weather, final String response) {
+    super(weather, response, GOrcs::new);
+  }
+
+}