diff --git a/async-method-invocation/pom.xml b/async-method-invocation/pom.xml
index be6aa3bca..de81eb0b7 100644
--- a/async-method-invocation/pom.xml
+++ b/async-method-invocation/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/async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutorTest.java b/async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutorTest.java
new file mode 100644
index 000000000..7db0abfce
--- /dev/null
+++ b/async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutorTest.java
@@ -0,0 +1,301 @@
+package com.iluwatar.async.method.invocation;
+
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Matchers;
+
+import java.util.Optional;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.timeout;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.when;
+import static org.mockito.internal.verification.VerificationModeFactory.times;
+
+/**
+ * Date: 12/6/15 - 10:49 AM
+ *
+ * @author Jeroen Meulemeester
+ */
+public class ThreadAsyncExecutorTest {
+
+	/**
+	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)}
+	 */
+	@Test(timeout = 3000)
+	public void testSuccessfulTaskWithoutCallback() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+
+		final Object result = new Object();
+		final Callable<Object> task = mock(Callable.class);
+		when(task.call()).thenReturn(result);
+
+		final AsyncResult<Object> asyncResult = executor.startProcess(task);
+		assertNotNull(asyncResult);
+		asyncResult.await(); // Prevent timing issues, and wait until the result is available
+		assertTrue(asyncResult.isCompleted());
+
+		// Our task should only execute once ...
+		verify(task, times(1)).call();
+
+		// ... and the result should be exactly the same object
+		assertSame(result, asyncResult.getValue());
+	}
+
+	/**
+	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
+	 */
+	@Test(timeout = 3000)
+	public void testSuccessfulTaskWithCallback() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+
+		final Object result = new Object();
+		final Callable<Object> task = mock(Callable.class);
+		when(task.call()).thenReturn(result);
+
+		final AsyncCallback callback = mock(AsyncCallback.class);
+		final AsyncResult<Object> asyncResult = executor.startProcess(task, callback);
+		assertNotNull(asyncResult);
+		asyncResult.await(); // Prevent timing issues, and wait until the result is available
+		assertTrue(asyncResult.isCompleted());
+
+		// Our task should only execute once ...
+		verify(task, times(1)).call();
+
+		// ... same for the callback, we expect our object
+		final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor.forClass((Class) Optional.class);
+		verify(callback, times(1)).onComplete(eq(result), optionalCaptor.capture());
+
+		final Optional<Exception> optionalException = optionalCaptor.getValue();
+		assertNotNull(optionalException);
+		assertFalse(optionalException.isPresent());
+
+		// ... and the result should be exactly the same object
+		assertSame(result, asyncResult.getValue());
+	}
+
+	/**
+	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)}
+	 * when a task takes a while to execute
+	 */
+	@Test(timeout = 5000)
+	public void testLongRunningTaskWithoutCallback() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+
+		final Object result = new Object();
+		final Callable<Object> task = mock(Callable.class);
+		when(task.call()).thenAnswer(i -> {
+			Thread.sleep(1500);
+			return result;
+		});
+
+		final AsyncResult<Object> asyncResult = executor.startProcess(task);
+		assertNotNull(asyncResult);
+		assertFalse(asyncResult.isCompleted());
+
+		try {
+			asyncResult.getValue();
+			fail("Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
+		} catch (IllegalStateException e) {
+			assertNotNull(e.getMessage());
+		}
+
+		// Our task should only execute once, but it can take a while ...
+		verify(task, timeout(3000).times(1)).call();
+
+		// Prevent timing issues, and wait until the result is available
+		asyncResult.await();
+		assertTrue(asyncResult.isCompleted());
+		verifyNoMoreInteractions(task);
+
+		// ... and the result should be exactly the same object
+		assertSame(result, asyncResult.getValue());
+	}
+
+	/**
+	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
+	 * when a task takes a while to execute
+	 */
+	@Test(timeout = 5000)
+	public void testLongRunningTaskWithCallback() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+
+		final Object result = new Object();
+		final Callable<Object> task = mock(Callable.class);
+		when(task.call()).thenAnswer(i -> {
+			Thread.sleep(1500);
+			return result;
+		});
+
+		final AsyncCallback<Object> callback = mock(AsyncCallback.class);
+		final AsyncResult<Object> asyncResult = executor.startProcess(task, callback);
+		assertNotNull(asyncResult);
+		assertFalse(asyncResult.isCompleted());
+
+		verifyZeroInteractions(callback);
+
+		try {
+			asyncResult.getValue();
+			fail("Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
+		} catch (IllegalStateException e) {
+			assertNotNull(e.getMessage());
+		}
+
+		// Our task should only execute once, but it can take a while ...
+		verify(task, timeout(3000).times(1)).call();
+
+		final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor.forClass((Class) Optional.class);
+		verify(callback, timeout(3000).times(1)).onComplete(eq(result), optionalCaptor.capture());
+
+		final Optional<Exception> optionalException = optionalCaptor.getValue();
+		assertNotNull(optionalException);
+		assertFalse(optionalException.isPresent());
+
+		// Prevent timing issues, and wait until the result is available
+		asyncResult.await();
+		assertTrue(asyncResult.isCompleted());
+		verifyNoMoreInteractions(task, callback);
+
+		// ... and the result should be exactly the same object
+		assertSame(result, asyncResult.getValue());
+	}
+
+	/**
+	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)}
+	 * when a task takes a while to execute, while waiting on the result using {@link ThreadAsyncExecutor#endProcess(AsyncResult)}
+	 */
+	@Test(timeout = 5000)
+	public void testEndProcess() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+
+		final Object result = new Object();
+		final Callable<Object> task = mock(Callable.class);
+		when(task.call()).thenAnswer(i -> {
+			Thread.sleep(1500);
+			return result;
+		});
+
+		final AsyncResult<Object> asyncResult = executor.startProcess(task);
+		assertNotNull(asyncResult);
+		assertFalse(asyncResult.isCompleted());
+
+		try {
+			asyncResult.getValue();
+			fail("Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
+		} catch (IllegalStateException e) {
+			assertNotNull(e.getMessage());
+		}
+
+		assertSame(result, executor.endProcess(asyncResult));
+		verify(task, times(1)).call();
+		assertTrue(asyncResult.isCompleted());
+
+		// Calling end process a second time while already finished should give the same result
+		assertSame(result, executor.endProcess(asyncResult));
+		verifyNoMoreInteractions(task);
+	}
+
+	/**
+	 * Test used to verify the behaviour of {@link ThreadAsyncExecutor#startProcess(Callable)}
+	 * when the callable is 'null'
+	 */
+	@Test(timeout = 3000)
+	public void testNullTask() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+		final AsyncResult<Object> asyncResult = executor.startProcess(null);
+
+		assertNotNull("The AsyncResult should not be 'null', even though the task was 'null'.", asyncResult);
+		asyncResult.await(); // Prevent timing issues, and wait until the result is available
+		assertTrue(asyncResult.isCompleted());
+
+		try {
+			asyncResult.getValue();
+			fail("Expected ExecutionException with NPE as cause");
+		} catch (final ExecutionException e) {
+			assertNotNull(e.getMessage());
+			assertNotNull(e.getCause());
+			assertEquals(NullPointerException.class, e.getCause().getClass());
+		}
+
+	}
+
+	/**
+	 * Test used to verify the behaviour of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
+	 * when the callable is 'null', but the asynchronous callback is provided
+	 */
+	@Test(timeout = 3000)
+	public void testNullTaskWithCallback() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+		final AsyncCallback<Object> callback = mock(AsyncCallback.class);
+		final AsyncResult<Object> asyncResult = executor.startProcess(null, callback);
+
+		assertNotNull("The AsyncResult should not be 'null', even though the task was 'null'.", asyncResult);
+		asyncResult.await(); // Prevent timing issues, and wait until the result is available
+		assertTrue(asyncResult.isCompleted());
+
+		final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor.forClass((Class) Optional.class);
+		verify(callback, times(1)).onComplete(Matchers.isNull(), optionalCaptor.capture());
+
+		final Optional<Exception> optionalException = optionalCaptor.getValue();
+		assertNotNull(optionalException);
+		assertTrue(optionalException.isPresent());
+
+		final Exception exception = optionalException.get();
+		assertNotNull(exception);
+		assertEquals(NullPointerException.class, exception.getClass());
+
+		try {
+			asyncResult.getValue();
+			fail("Expected ExecutionException with NPE as cause");
+		} catch (final ExecutionException e) {
+			assertNotNull(e.getMessage());
+			assertNotNull(e.getCause());
+			assertEquals(NullPointerException.class, e.getCause().getClass());
+		}
+
+	}
+
+	/**
+	 * Test used to verify the behaviour of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
+	 * when both the callable and the asynchronous callback are 'null'
+	 */
+	@Test(timeout = 3000)
+	public void testNullTaskWithNullCallback() throws Exception {
+		// Instantiate a new executor and start a new 'null' task ...
+		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+		final AsyncResult<Object> asyncResult = executor.startProcess(null, null);
+
+		assertNotNull("The AsyncResult should not be 'null', even though the task and callback were 'null'.", asyncResult);
+		asyncResult.await(); // Prevent timing issues, and wait until the result is available
+		assertTrue(asyncResult.isCompleted());
+
+		try {
+			asyncResult.getValue();
+			fail("Expected ExecutionException with NPE as cause");
+		} catch (final ExecutionException e) {
+			assertNotNull(e.getMessage());
+			assertNotNull(e.getCause());
+			assertEquals(NullPointerException.class, e.getCause().getClass());
+		}
+
+	}
+
+}
\ No newline at end of file