Added tests for memento pattern

memento/src/test/java/com/iluwatar/memento/StarTest.java

@@ -0,0 +1,75 @@
+package com.iluwatar.memento;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Date: 12/20/15 - 10:08 AM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class StarTest {
+
+  /**
+   * Verify the stages of a dying sun, without going back in time
+   */
+  @Test
+  public void testTimePasses() {
+    final Star star = new Star(StarType.SUN, 1, 2);
+    assertEquals("sun age: 1 years mass: 2 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("red giant age: 2 years mass: 16 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("white dwarf age: 4 years mass: 128 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("supernova age: 8 years mass: 1024 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("dead star age: 16 years mass: 8192 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("dead star age: 64 years mass: 0 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("dead star age: 256 years mass: 0 tons", star.toString());
+  }
+
+  /**
+   * Verify some stage of a dying sun, but go back in time to test the memento
+   */
+  @Test
+  public void testSetMemento() {
+    final Star star = new Star(StarType.SUN, 1, 2);
+    final StarMemento firstMemento = star.getMemento();
+    assertEquals("sun age: 1 years mass: 2 tons", star.toString());
+
+    star.timePasses();
+    final StarMemento secondMemento = star.getMemento();
+    assertEquals("red giant age: 2 years mass: 16 tons", star.toString());
+
+    star.timePasses();
+    final StarMemento thirdMemento = star.getMemento();
+    assertEquals("white dwarf age: 4 years mass: 128 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("supernova age: 8 years mass: 1024 tons", star.toString());
+
+    star.setMemento(thirdMemento);
+    assertEquals("white dwarf age: 4 years mass: 128 tons", star.toString());
+
+    star.timePasses();
+    assertEquals("supernova age: 8 years mass: 1024 tons", star.toString());
+
+    star.setMemento(secondMemento);
+    assertEquals("red giant age: 2 years mass: 16 tons", star.toString());
+
+    star.setMemento(firstMemento);
+    assertEquals("sun age: 1 years mass: 2 tons", star.toString());
+
+  }
+
+}