Android: Writing test cases for Fragments

Here's a rough guide using ActivityInstrumentationTestCase2:

Step 1. Create a blank Activity to hold your fragment(s)

  private static class FragmentUtilActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      LinearLayout view = new LinearLayout(this);
      view.setId(1);

      setContentView(view);
    }
  }

Step 2: Inside your test, instantiate your fragment and add it to the blank activity

public class MyFragmentTest extends ActivityInstrumentationTestCase2<FragmentUtilActivity> { 
    private MyFragment fragment;

    @Before
    public void setup() {
        fragment = new MyFragment();
        getActivity().getFragmentManager().beginTransaction().add(1, fragment, null).commit();
    }
}

Step 3 Test your instantiated fragment

@Test
public void aTest() {
    fragment.getView().findViewById(...);
}

---

If you're using robolectric, this is pretty straightforward using the FragmentUtilTest class:

@Test
public void aTest() {
    // instantiate your fragment
    MyFragment fragment = new MyFragment();

    // Add it to a blank activity
    FragmentTestUtil.startVisibleFragment(fragment);

    // ... call getView().findViewById() on your fragment
}

Here is my working solution:

1. Create an instrumentation unit test class for this in androidTest directory, i.e.:

   public class FragmentTest extends 
   ActivityInstrumentationTestCase2<MainActivity> {
        private MainActivity testingActivity;
        private TestFragment testFragment;
        //... 
   }
   

2. call this constructor inside this new class:

   public FragmentTest() {
   
       super(MainActivity.class);
   }
   

3. override the setUp() method (be sure to have R.id.fragmentContainer in your Activity class) where you will call at the end waitForIdleSync():

   @Override
   protected void setUp() throws Exception {
       super.setUp();
   
       // Starts the activity under test using
       // the default Intent with:
       // action = {@link Intent#ACTION_MAIN}
       // flags = {@link Intent#FLAG_ACTIVITY_NEW_TASK}
       // All other fields are null or empty.
       testingActivity = getActivity();
   
       testFragment = new TestFragment();
       testingActivity.getFragmentManager().beginTransaction().add(R.id.fragmentContainer,testFragment,null).commit();
       /**
        * Synchronously wait for the application to be idle.  Can not be called
        * from the main application thread -- use {@link #start} to execute
        * instrumentation in its own thread.
        *
        * Without waitForIdleSync(); our test would have nulls in fragment references.
        */
       getInstrumentation().waitForIdleSync();
   }
   

4. Write a test method, for example somethng like:

   public void testGameFragmentsTextViews() {
   
      String empty = "";
      TextView textView = (TextView)testFragment.getView().findViewById(R.id.myTextView);
      assertTrue("Empty stuff",(textView.getText().equals(empty)));   
   }
   

5. Run the test.