JUnit testing for Android app with fragments

Question

My Android App was built on Single Activity, multiple fragments based model. I need to do unit testing for the app. I could write unit testcases for app which contains all activities using ActivityInstrumentationTestCase2 JUnit but not for app which contains fragments. Please suggest the way to write JUnit testcases for fragments.

Thank you

Answer 1

See Android: Testing fragments

Copied for your reading pleasure with edits made for getFragmentManager() vs getSupportFragmentManager() and android:exported="false":

If you want to test a fragment in isolation, you need to create a Test FragmentActivity so your test can use that. The test activity will look something like this. Remember to declare it in your application’s manifest:

 public class TestFragmentActivity extends FragmentActivity {
   @Override
   protected void onCreate(Bundle arg0) {
     super.onCreate(arg0);
     setContentView(R.layout.activity_fortests);
   }
 }

Layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
   <LinearLayout
        android:id="@+id/activity_test_fragment_linearlayout"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        />
 </RelativeLayout>

AndroidManifest:

 ...
 <activity
  android:name="your.package.name.TestFragmentActivity"
  android:exported="false" />
 ...

Then in your test project, you can have a class like this to start the fragment:

  public class FrameworkObjectsGeneratorFragmentTest 
      extends ActivityInstrumentationTestCase2<TestFragmentActivity> {
    private TestFragmentActivity mActivity;

    public FrameworkObjectsGeneratorFragmentTest() {
      super(TestFragmentActivity.class);
    }

    @Override
    protected void setUp() throws Exception {
      super.setUp();
      mActivity = getActivity();
    }

    private Fragment startFragment(Fragment fragment) {
      FragmentTransaction transaction = mActivity.getFragmentManager().beginTransaction();
      transaction.add(R.id.activity_test_fragment_linearlayout, fragment, "tag");
      transaction.commit();
      getInstrumentation().waitForIdleSync();
      Fragment frag = mActivity.getFragmentManager().findFragmentByTag("tag");
      return frag;
    }

   public void testFragment() {
      FrameworkObjectsGeneratorFragment fragment = new FrameworkObjectsGeneratorFragment() {
         //Override methods and add assertations here.
      };

      Fragment frag = startFragment(fragment);
    }
  }

The startFragment() method adds a fragment you specify to the ViewGroup in the TestActivity.

The good thing about testing fragments, as opposed to Activities, is that you can extends the Fragment to override protected fields and methods within which you can add assertions.

NOTE: Call getSupportFragmentManager() if you are using the support library.