Sample Robolectric UI Test https://hackernoon.com/yet-another-mvp-article-part-5-writing-test-using-a-mixture-of-dagger-and-espresso-15c638182706

MainActivityRobolectricTest.java

package com.mirhoseini.marvel.activity;

/*...*/

@RunWith(RobolectricTestRunner.class)
@Config(constants = BuildConfig.class, sdk = 21, shadows = {ShadowSnackbar.class})
public class MainActivityRobolectricTest {

    private final static String TEST_TEXT = "This is a test text.";
    private MainActivity activity;

    @Before
    public void setUp() throws Exception {
        activity = Robolectric.setupActivity(MainActivity.class);

        assertNotNull(activity);
    }

    @Test
    public void testShowToastMessage() throws Exception {
        activity.showMessage(TEST_TEXT);

        assertThat(TEST_TEXT, equalTo(ShadowToast.getTextOfLatestToast()));
    }

    @Test
    public void testShowOfflineMessage() throws Exception {
        activity.showOfflineMessage();

        assertSnackbarIsShown(R.string.offline_message);
    }
}