// MainActivityTest.java

// Static imports for assertion methods
import static junit.framework.Assert.assertNotNull;
import static junit.framework.Assert.assertTrue;

@Config(constants = BuildConfig.class, sdk = Build.VERSION_CODES.LOLLIPOP)
@RunWith(RobolectricTestRunner.class)
public class MainActivityTest {
private MainActivity activity;

// @Before => JUnit 4 annotation that specifies this method should run before each test is run
// Useful to do setup for objects that are needed in the test
@Before
public void setup() {
    // Convenience method to run MainActivity through the Activity Lifecycle methods:
    // onCreate(...) => onStart() => onPostCreate(...) => onResume()
    activity = Robolectric.setupActivity(MainActivity.class);
}

// @Test => JUnit 4 annotation specifying this is a test to be run
// The test simply checks that our TextView exists and has the text "Hello world!"
@Test
public void validateTextViewContent() {
    TextView tvHelloWorld = (TextView) activity.findViewById(R.id.tvHelloWorld);
    assertNotNull("TextView could not be found", tvHelloWorld);
    assertTrue("TextView contains incorrect text",
        "Hello world!".equals(tvHelloWorld.getText().toString()));
}
}