#10 effective java: item 3

effective-java/src/test/java/com/example/effectivejava/chapter01/item03/field/ConcertTest.java

@@ -0,0 +1,17 @@
+package com.example.effectivejava.chapter01.item03.field;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ConcertTest {
+
+    @Test
+    void perform() {
+        Concert concert = new Concert(new MockElvis());
+        concert.perform();
+
+        assertTrue(concert.isLightsOn());
+        assertTrue(concert.isMainStateOpen());
+    }
+}

effective-java/src/test/java/com/example/effectivejava/chapter01/item03/field/MockElvis.java

@@ -0,0 +1,13 @@
+package com.example.effectivejava.chapter01.item03.field;
+
+public class MockElvis implements IElvis {
+    @Override
+    public void leaveTheBuilding() {
+
+    }
+
+    @Override
+    public void sing() {
+        System.out.println("You ain't nothin' but a hound dog.");
+    }
+}