Added testPopFromHeightOneSize

src/test/java/MyStackTest.java

@@ -45,4 +45,11 @@ public class MyStackTest {
         pushDummies(1);
         assertEquals(1, stack.pop());
     }
+
+    @Test
+    public void testPopFromHeightOneSize() {
+        pushDummies(1);
+        stack.pop();
+        assertEquals(0,stack.size());
+    }
 }
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