Created size() stub so we can test the size.

/tag have-size-stub

src/main/java/MyStack.java

@@ -2,4 +2,8 @@ public class MyStack {
     public MyStack() {
         super();
     }
+
+    public int size() {
+        return Integer.MIN_VALUE;
+    }
 }

src/test/java/MyStackTest.java

 import org.junit.After;
 import org.junit.Before;
+import org.junit.Test;
 
 import static org.junit.Assert.*;
 
@@ -15,4 +16,9 @@ public class MyStackTest {
     @After
     public void tearDown() {
     }
+
+    @Test
+    public void testEmptyStack() {
+        fail("need to ");
+    }
 }
\ No newline at end of file