Adding marker interfaces UT

core-java-lang-oop/src/test/java/com/baeldung/markerinterface/MarkerInterfaceUnitTest.java

@@ -0,0 +1,26 @@
+package com.baeldung.markerinterface;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class MarkerInterfaceUnitTest {
+
+    @Test
+    public void givenDeletableObjectThenTrueReturned() {
+        ShapeDao shapeDao = new ShapeDao();
+        Object rectangle = new Rectangle(2, 3);
+
+        boolean result = shapeDao.delete(rectangle);
+        assertEquals(true, result);
+    }
+    
+    @Test
+    public void givenNonDeletableObjectThenFalseReturned() {
+        ShapeDao shapeDao = new ShapeDao();
+        Object object = new Object();
+
+        boolean result = shapeDao.delete(object);
+        assertEquals(false, result);
+    }
+}