Add proper tests for flyweight pattern

flyweight/src/test/java/com/iluwatar/flyweight/AlchemistShopTest.java

@@ -0,0 +1,40 @@
+package com.iluwatar.flyweight;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * Date: 12/12/15 - 10:54 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class AlchemistShopTest {
+
+  @Test
+  public void testShop() throws Exception {
+    final AlchemistShop shop = new AlchemistShop();
+
+    final List<Potion> bottomShelf = shop.getBottomShelf();
+    assertNotNull(bottomShelf);
+    assertEquals(5, bottomShelf.size());
+
+    final List<Potion> topShelf = shop.getTopShelf();
+    assertNotNull(topShelf);
+    assertEquals(8, topShelf.size());
+
+    final List<Potion> allPotions = new ArrayList<>();
+    allPotions.addAll(topShelf);
+    allPotions.addAll(bottomShelf);
+
+    // There are 13 potion instances, but only 5 unique instance types
+    assertEquals(13, allPotions.size());
+    assertEquals(5, allPotions.stream().map(System::identityHashCode).distinct().count());
+
+  }
+
+}