How can I test fragments with Robolectric?

Question

I know there is a Robolectric.shadowOf(Fragment) method and a ShadowFragment class, thought they aren\'t listed on the docs, but I can\'t make it w

Answer 1

Edit #4 & #5: In Robolectric 3.*, they split up the fragment starting functions.

For support fragments, you will need to add a dependency to your build.gradle:

testCompile "org.robolectric:shadows-supportv4:3.8"

Import: org.robolectric.shadows.support.v4.SupportFragmentTestUtil.startFragment;

For platform fragments, you don't need this dependency. Import: import static org.robolectric.util.FragmentTestUtil.startFragment;

They both use the same name of startFragment().

import static org.robolectric.shadows.support.v4.SupportFragmentTestUtil.startFragment;

@RunWith(RobolectricTestRunner.class)
@Config(constants = BuildConfig.class)
public class YourFragmentTest
{
    @Test
    public void shouldNotBeNull() throws Exception
    {
        YourFragment fragment = YourFragment.newInstance();
        startFragment( fragment );
        assertNotNull( fragment );
    }
}

Edit #3: Robolectric 2.4 has an API for support and regular fragments. You can either use the newInstance() pattern or use the constructor when constructing your Fragment's.

import org.junit.Test;
import org.junit.runner.RunWith;
import static org.junit.Assert.assertNotNull;
import static org.robolectric.util.FragmentTestUtil.startFragment;

@RunWith(RobolectricGradleTestRunner.class)
public class YourFragmentTest
{
    @Test
    public void shouldNotBeNull() throws Exception
    {
        YourFragment fragment = new YourFragment();
        startFragment( fragment );
        assertNotNull( fragment );
    }
}

Edit #2: There's a new helper if you're using support fragments (one that supports regular activities/fragments should be in the next release):

import static org.robolectric.util.FragmentTestUtil.startFragment;

@Before
public void setUp() throws Exception
{
    fragment = YourFragment.newInstance();
    startFragment( fragment );
}

Edit: If you upgraded to Robolectric 2.0:

public static void startFragment( Fragment fragment )
{
    FragmentActivity activity = Robolectric.buildActivity( FragmentActivity.class )
                                           .create()
                                           .start()
                                           .resume()
                                           .get();

    FragmentManager fragmentManager = activity.getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction.add( fragment, null );
    fragmentTransaction.commit();
}

Original answer

As the other commenter suggested, you do need to use the fragment manager (instead of calling the lifecycle methods you listed above).

@RunWith(MyTestRunner.class)
public class YourFragmentTest
{
    @Test
    public void shouldNotBeNull() throws Exception
    {
        YourFragment yourFragment = new YourFragment();
        startFragment( yourFragment );
        assertNotNull( yourFragment );
    }

I create a test runner and have a function that starts up a fragment for me so I can use it everywhere.

public class MyTestRunner extends RobolectricTestRunner
{
    public MyTestRunner( Class testClass ) throws InitializationError
    {
        super( testClass );
    }

    public static void startFragment( Fragment fragment )
    {
        FragmentManager fragmentManager = new FragmentActivity().getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add( fragment, null );
        fragmentTransaction.commit();
    }
}