diff --git a/adapter/pom.xml b/adapter/pom.xml
index 2284c2974..ddb81441f 100644
--- a/adapter/pom.xml
+++ b/adapter/pom.xml
@@ -14,5 +14,10 @@
       <artifactId>junit</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 </project>
diff --git a/adapter/src/main/java/com/iluwatar/adapter/App.java b/adapter/src/main/java/com/iluwatar/adapter/App.java
index f912efb03..d2353eec4 100644
--- a/adapter/src/main/java/com/iluwatar/adapter/App.java
+++ b/adapter/src/main/java/com/iluwatar/adapter/App.java
@@ -1,30 +1,28 @@
 package com.iluwatar.adapter;
 
 /**
- *
  * An adapter helps two incompatible interfaces to work together. This is the real world definition
  * for an adapter. Interfaces may be incompatible but the inner functionality should suit the need.
  * The Adapter design pattern allows otherwise incompatible classes to work together by converting
  * the interface of one class into an interface expected by the clients.
- * <p>
- * There are two variations of the Adapter pattern: The class adapter implements the adaptee's
+ * 
+ * <p>There are two variations of the Adapter pattern: The class adapter implements the adaptee's
  * interface whereas the object adapter uses composition to contain the adaptee in the adapter
  * object. This example uses the object adapter approach.
- * <p>
- * The Adapter ({@link GnomeEngineer}) converts the interface of the target class (
+ * 
+ * <p>The Adapter ({@link GnomeEngineer}) converts the interface of the target class (
  * {@link GoblinGlider}) into a suitable one expected by the client ({@link GnomeEngineeringManager}
  * ).
- * 
  */
 public class App {
 
   /**
-   * Program entry point
-   * 
+   * Program entry point.
+   *
    * @param args command line args
    */
   public static void main(String[] args) {
-    Engineer manager = new GnomeEngineeringManager();
+    Engineer manager = new GnomeEngineeringManager(new GnomeEngineer());
     manager.operateDevice();
   }
 }
diff --git a/adapter/src/main/java/com/iluwatar/adapter/GnomeEngineeringManager.java b/adapter/src/main/java/com/iluwatar/adapter/GnomeEngineeringManager.java
index a2faf1e54..ff4ddb617 100644
--- a/adapter/src/main/java/com/iluwatar/adapter/GnomeEngineeringManager.java
+++ b/adapter/src/main/java/com/iluwatar/adapter/GnomeEngineeringManager.java
@@ -1,20 +1,26 @@
 package com.iluwatar.adapter;
 
 /**
- * 
  * GnomeEngineering manager uses {@link Engineer} to operate devices.
- * 
  */
 public class GnomeEngineeringManager implements Engineer {
 
   private Engineer engineer;
 
   public GnomeEngineeringManager() {
-    engineer = new GnomeEngineer();
+
+  }
+
+  public GnomeEngineeringManager(Engineer engineer) {
+    this.engineer = engineer;
   }
 
   @Override
   public void operateDevice() {
     engineer.operateDevice();
   }
+
+  public void setEngineer(Engineer engineer) {
+    this.engineer = engineer;
+  }
 }
diff --git a/adapter/src/test/java/com/iluwatar/adapter/AdapterPatternTest.java b/adapter/src/test/java/com/iluwatar/adapter/AdapterPatternTest.java
new file mode 100644
index 000000000..866bfb968
--- /dev/null
+++ b/adapter/src/test/java/com/iluwatar/adapter/AdapterPatternTest.java
@@ -0,0 +1,68 @@
+package com.iluwatar.adapter;
+
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * An adapter helps two incompatible interfaces to work together. This is the real world definition
+ * for an adapter. Interfaces may be incompatible but the inner functionality should suit the need.
+ * The Adapter design pattern allows otherwise incompatible classes to work together by converting
+ * the interface of one class into an interface expected by the clients.
+ * 
+ * <p>There are two variations of the Adapter pattern: 
+ * The class adapter implements the adaptee's
+ * interface whereas the object adapter uses composition to contain the adaptee in the adapter
+ * object. This example uses the object adapter approach.
+ * 
+ * <p>The Adapter ({@link GnomeEngineer}) converts the interface 
+ * of the target class ({@link GoblinGlider}) into a suitable one expected by 
+ * the client ({@link GnomeEngineeringManager}
+ * ).
+ */
+public class AdapterPatternTest {
+
+  private Map<String, Object> beans;
+
+  private static final String ENGINEER_BEAN = "engineer";
+
+  private static final String MANAGER_BEAN = "manager";
+
+  /**
+   * This method runs before the test execution and sets the bean objects in the beans Map.
+   */
+  @Before
+  public void setup() {
+    beans = new HashMap<>();
+
+    GnomeEngineer gnomeEngineer = spy(new GnomeEngineer());
+    beans.put(ENGINEER_BEAN, gnomeEngineer);
+
+    GnomeEngineeringManager manager = new GnomeEngineeringManager();
+    manager.setEngineer((GnomeEngineer) beans.get(ENGINEER_BEAN));
+    beans.put(MANAGER_BEAN, manager);
+  }
+
+  /**
+   * This test asserts that when we call operateDevice() method on a manager bean, it is internally
+   * calling operateDevice method on the engineer object. The Adapter ({@link GnomeEngineer})
+   * converts the interface of the target class ( {@link GoblinGlider}) into a suitable one expected
+   * by the client ({@link GnomeEngineeringManager} ).
+   */
+  @Test
+  public void testAdapter() {
+    Engineer manager = (Engineer) beans.get(MANAGER_BEAN);
+
+    // when manager is asked to operate device
+    manager.operateDevice();
+
+    // Manager internally calls the engineer object to operateDevice
+    Engineer engineer = (Engineer) beans.get(ENGINEER_BEAN);
+    verify(engineer).operateDevice();
+  }
+}
diff --git a/adapter/src/test/java/com/iluwatar/adapter/AppTest.java b/adapter/src/test/java/com/iluwatar/adapter/AppTest.java
deleted file mode 100644
index a7462bd9a..000000000
--- a/adapter/src/test/java/com/iluwatar/adapter/AppTest.java
+++ /dev/null
@@ -1,19 +0,0 @@
-package com.iluwatar.adapter;
-
-import org.junit.Test;
-
-import com.iluwatar.adapter.App;
-
-/**
- * 
- * Application test
- *
- */
-public class AppTest {
-
-  @Test
-  public void test() {
-    String[] args = {};
-    App.main(args);
-  }
-}