#502 Adjusted tests for logger introduction

event-aggregator/src/test/java/com/iluwatar/event/aggregator/KingJoffreyTest.java

@@ -22,17 +22,18 @@
  */
 package com.iluwatar.event.aggregator;
 
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.AppenderBase;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import org.slf4j.LoggerFactory;
 
-import java.io.PrintStream;
+import java.util.LinkedList;
+import java.util.List;
 
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.times;
-import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.verifyZeroInteractions;
-import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.junit.Assert.assertEquals;
 
 /**
  * Date: 12/12/15 - 3:04 PM
@@ -41,31 +42,16 @@ import static org.mockito.Mockito.verifyNoMoreInteractions;
  */
 public class KingJoffreyTest {
 
-  /**
-   * The mocked standard out {@link PrintStream}, required since {@link KingJoffrey} does nothing
-   * except for writing to std-out using {@link System#out}
-   */
-  private final PrintStream stdOutMock = mock(PrintStream.class);
+  private InMemoryAppender appender;
 
-  /**
-   * 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);
+    appender = new InMemoryAppender(KingJoffrey.class);
   }
 
-  /**
-   * Removed the mocked std-out {@link PrintStream} again from the {@link System} class
-   */
   @After
   public void tearDown() {
-    System.setOut(this.stdOutOrig);
+    appender.stop();
   }
 
   /**
@@ -75,15 +61,38 @@ public class KingJoffreyTest {
   public void testOnEvent() {
     final KingJoffrey kingJoffrey = new KingJoffrey();
 
-    for (final Event event : Event.values()) {
-      verifyZeroInteractions(this.stdOutMock);
+    for (int i = 0; i < Event.values().length; ++i) {
+      assertEquals(i, appender.getLogSize());
+      Event event = Event.values()[i];
       kingJoffrey.onEvent(event);
 
       final String expectedMessage = "Received event from the King's Hand: " + event.toString();
-      verify(this.stdOutMock, times(1)).println(expectedMessage);
-      verifyNoMoreInteractions(this.stdOutMock);
+      assertEquals(expectedMessage, appender.getLastMessage());
+      assertEquals(i + 1, appender.getLogSize());
     }
 
   }
 
-}
+  private class InMemoryAppender extends AppenderBase<ILoggingEvent> {
+    private List<ILoggingEvent> log = new LinkedList<>();
+
+    public InMemoryAppender(Class clazz) {
+      ((Logger) LoggerFactory.getLogger(clazz)).addAppender(this);
+      start();
+    }
+
+    @Override
+    protected void append(ILoggingEvent eventObject) {
+      log.add(eventObject);
+    }
+
+    public String getLastMessage() {
+      return log.get(log.size() - 1).getFormattedMessage();
+    }
+
+    public int getLogSize() {
+      return log.size();
+    }
+  }
+
+}