Added UnitTest cases for command.

command/pom.xml

@@ -14,5 +14,10 @@
       <artifactId>junit</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>

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

@@ -1,19 +0,0 @@
-package com.iluwatar.command;
-
-import org.junit.Test;
-
-import com.iluwatar.command.App;
-
-/**
- * 
- * Application test
- *
- */
-public class AppTest {
-
-  @Test
-  public void test() {
-    String[] args = {};
-    App.main(args);
-  }
-}

command/src/test/java/com/iluwatar/command/CommandTest.java

@@ -0,0 +1,71 @@
+package com.iluwatar.command;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+/**
+ * The Command pattern is a behavioral design pattern in which an object is used to encapsulate all
+ * information needed to perform an action or trigger an event at a later time. This information
+ * includes the method name, the object that owns the method and values for the method parameters.
+ * 
+ * <p>Four terms always associated with the command pattern are command, receiver, invoker and 
+ * client. A command object (spell) knows about the receiver (target) and invokes a method of 
+ * the receiver.Values for parameters of the receiver method are stored in the command. The receiver
+ * then does the work. An invoker object (wizard) knows how to execute a command, and optionally 
+ * does bookkeeping about the command execution. The invoker does not know anything about a 
+ * concrete command, it knows only about command interface. Both an invoker object and several 
+ * command objects are held by a client object (app). The client decides which commands to execute
+ * at which points. To execute a command, it passes the command object to the invoker object.
+ */
+public class CommandTest {
+
+  private static final String GOBLIN = "Goblin";
+
+  /**
+   * This test verifies that when the wizard casts spells on the goblin. The wizard keeps track of
+   * the previous spells cast, so it is easy to undo them. In addition, it also verifies that the
+   * wizard keeps track of the spells undone, so they can be redone.
+   */
+  @Test
+  public void testCommand() {
+
+    Wizard wizard = new Wizard();
+    Goblin goblin = new Goblin();
+
+    wizard.castSpell(new ShrinkSpell(), goblin);
+    verifyGoblin(goblin, GOBLIN, Size.SMALL, Visibility.VISIBLE);
+
+    wizard.castSpell(new InvisibilitySpell(), goblin);
+    verifyGoblin(goblin, GOBLIN, Size.SMALL, Visibility.INVISIBLE);
+
+    wizard.undoLastSpell();
+    verifyGoblin(goblin, GOBLIN, Size.SMALL, Visibility.VISIBLE);
+
+    wizard.undoLastSpell();
+    verifyGoblin(goblin, GOBLIN, Size.NORMAL, Visibility.VISIBLE);
+
+    wizard.redoLastSpell();
+    verifyGoblin(goblin, GOBLIN, Size.SMALL, Visibility.VISIBLE);
+
+    wizard.redoLastSpell();
+    verifyGoblin(goblin, GOBLIN, Size.SMALL, Visibility.INVISIBLE);
+  }
+
+  /**
+   * This method asserts that the passed goblin object has the name as expectedName, size as
+   * expectedSize and visibility as expectedVisibility.
+   *
+   * @param goblin a goblin object whose state is to be verified against other parameters
+   * @param expectedName expectedName of the goblin
+   * @param expectedSize expected size of the goblin
+   * @param expectedVisibilty exepcted visibility of the goblin
+   */
+  private void verifyGoblin(Goblin goblin, String expectedName, Size expectedSize,
+      Visibility expectedVisibilty) {
+    assertEquals("Goblin's name must be same as expectedName", expectedName, goblin.toString());
+    assertEquals("Goblin's size must be same as expectedSize", expectedSize, goblin.getSize());
+    assertEquals("Goblin's visibility must be same as expectedVisibility", expectedVisibilty,
+        goblin.getVisibility());
+  }
+}