diff --git a/command/pom.xml b/command/pom.xml
index 08ff32d3b..6001ebc33 100644
--- a/command/pom.xml
+++ b/command/pom.xml
@@ -14,5 +14,10 @@
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()); + } +}