page.title=Creating Unit Tests
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<h2>This lesson teaches you to</h2>
<ol>
  <li><a href="#testcase">Create a Test Case for Activity Unit Testing</a>
  <li><a href="#test_method">Validate Launch of Another Activity</a>
</ol>

<h2>Try it out</h2>
<div class="download-box">
 <a href="http://developer.android.com/shareables/training/AndroidTestingFun.zip"
class="button">Download the demo</a>
 <p class="filename">AndroidTestingFun.zip</p>
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</div>
</div>

<p>An {@link android.app.Activity} unit test is an excellent way to quickly
verify the state of an {@link android.app.Activity} and its interactions with
other components in isolation (that is, disconnected from the rest of the
system). A unit test generally tests the smallest possible unit of code
(which could be a method, class, or component), without dependencies on system
or network resources. For example, you can write a unit test to check
that an {@link android.app.Activity} has the correct layout or that it
triggers an {@link android.content.Intent} object correctly.</p>
<p>Unit tests are generally not suitable for testing complex UI interaction
events with the system. Instead, you should use
the {@link android.test.ActivityInstrumentationTestCase2} class, as described
in <a href="activity-ui-testing.html">Testing UI Components</a>.</p>
<p>This lesson shows how you can write a unit test to verify that an
{@link android.content.Intent} is triggered to launch another
{@link android.app.Activity}.
Since the test runs in an isolated environment, the
{@link android.content.Intent}
is not actually sent to the Android system, but you can inspect that the
{@link android.content.Intent} object's payload data is accurate.</p>
<p>For a complete test case example, take a look at
{@code LaunchActivityTest.java} in the sample app.</p>

<p class="note"><strong>Note: </strong>To test against system or external
dependencies, you can use mock objects from a mocking
framework and inject them into your unit tests. To learn more about the mocking
framework provided by Android, see
<a href="{@docRoot}tools/testing/testing_android.html#MockObjectClasses}">Mock
Object Classes</a>.</p>

<h2 id="testcase">Create a Test Case for Activity Unit Testing</h2>
<p>The {@link android.test.ActivityUnitTestCase} class provides support for
isolated testing of a single {@link android.app.Activity}. To create a unit
test for your {@link android.app.Activity}, your test class should extend
{@link android.test.ActivityUnitTestCase}.</p>

<p>The {@link android.app.Activity} in an {@link android.test.ActivityUnitTestCase}
is not automatically started by Android Instrumentation. To start the
{@link android.app.Activity} in isolation, you need to explicitly call the
{@link android.test.ActivityUnitTestCase#startActivity(android.content.Intent, android.os.Bundle, java.lang.Object) startActivity()}
method, and pass in the {@link android.content.Intent} to
launch your target {@link android.app.Activity}.</p>

<p>For example:</p>
<pre>
public class LaunchActivityTest
        extends ActivityUnitTestCase&lt;LaunchActivity&gt; {
    ...

    &#64;Override
    protected void setUp() throws Exception {
        super.setUp();
        mLaunchIntent = new Intent(getInstrumentation()
                .getTargetContext(), LaunchActivity.class);
        startActivity(mLaunchIntent, null, null);
        final Button launchNextButton =
                (Button) getActivity()
                .findViewById(R.id.launch_next_activity_button);
    }
}
</pre>

<h2 id="test_method">Validate Launch of Another Activity</h2>
<p id="test_goals">Your unit testing goals might include:</p>
<ul>
<li>Verifying that {@code LaunchActivity} fires an
{@link android.content.Intent} when a button is pushed clicked.</li>
<li>Verifying that the launched {@link android.content.Intent} contains the
correct payload data.</li>
</ul>

<p>To verify if an {@link android.content.Intent} was triggered
following the {@link android.widget.Button} click, you can use the
{@link android.test.ActivityUnitTestCase#getStartedActivityIntent()} method.
By using assertion methods, you can verify that the returned
{@link android.content.Intent} is not null, and that it contains the expected
string value to launch the next {@link android.app.Activity}. If both assertions
evaluate to {@code true}, you've successfully verified that the
{@link android.content.Intent} was correctly sent by your
{@link android.app.Activity}.</p>

<p>You might implement your test method like this:</p>
<pre>
&#64;MediumTest
public void testNextActivityWasLaunchedWithIntent() {
    startActivity(mLaunchIntent, null, null);
    final Button launchNextButton =
            (Button) getActivity()
            .findViewById(R.id.launch_next_activity_button);
    launchNextButton.performClick();

    final Intent launchIntent = getStartedActivityIntent();
    assertNotNull("Intent was null", launchIntent);
    assertTrue(isFinishCalled());

    final String payload =
            launchIntent.getStringExtra(NextActivity.EXTRAS_PAYLOAD_KEY);
    assertEquals("Payload is empty", LaunchActivity.STRING_PAYLOAD, payload);
}
</pre>
<p>Because {@code LaunchActivity} runs in isolation, you cannot use the
{@link android.test.TouchUtils} library to manipulate UI controls. To directly
click a {@link android.widget.Button}, you can call the
{@link android.view.View#performClick()} method instead.</p>