Java – How do I test abstract classes with Espresso?

Suppose I created an abstract with Toolbar BaseActivity, like this:

/**
 * A base activity that handles common functionality in the app. 
 * This includes the Toolbar
 */
public abstract class BaseActivity extends AppCompatActivity {
     Primary toolbar
    private Toolbar mToolbar;

@Override
    public void setContentView(int layoutResId) {
        super.setContentView(layoutResId);
        setToolbar();
    }

private void setToolbar() {
        if (mToolbar == null) {
            mToolbar = (Toolbar) findViewById(R.id.toolbar);
            if (mToolbar != null) {              
                mToolbar.setNavigationContentDescription(getResources().getString(
                    R.string.navigation_drawer_description_ally));
            setSupportActionBar(mToolbar);
            }
        }
    }
}

There is also a MainActivity that extends this BaseActivity as follows:

public class MainActivity extends BaseActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

The layout is:

toolbar.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimary"
    android:elevation="@dimen/spacing_tiny"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    android:popupTheme="@style/ThemeOverlay.AppCompat.Light"
    android:fitsSystemWindows="true"
    android:minHeight="?attr/actionBarSize"
    >

</android.support.v7.widget.Toolbar>

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=". MainActivity"
    >

<include
        layout="@layout/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        />

</LinearLayout>

My question is: how to test BaseActivity with espresso ？ For example, check if the toolbar exists?

You should create a TestActivity to test your abstract BaseActivity class. Keep in mind, however, that this class should only cover the necessary methods and code to avoid any impact on the BaseActivity class.

public class TestActivity extends BaseActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

Then you can use Espresso

@RunWith(AndroidJUnit4.class)
@SmallTest
public class BaseActivityTest {
    @Rule
    public ActivityTestRule<TestActivity> mTestActivityActivityTestRule = new ActivityTestRule<TestActivity>(TestActivity.class, true, false);
    @Before
    public void set() {
        setup your things
    }
    @Test
    public void testRequest1() {
        mTestActivityActivityTestRule.launchActivity(new Intent());
    }
}