Espresso 2.0 - Method annotated with @Test inside class extending junit3 testcase

Question

I got a weird warning Method annotated with @Test inside class extending junit3 testcase when using the new ActivityInstrumentationTestCase2 class shipped with Espresso 2.0.

My class looks just like the one that Google provided as an example:

import android.support.test.InstrumentationRegistry;
import android.support.test.runner.AndroidJUnit4;
import android.test.ActivityInstrumentationTestCase2;
import android.test.suitebuilder.annotation.LargeTest;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

import static android.support.test.espresso.matcher.ViewMatchers.assertThat;
import static org.hamcrest.Matchers.notNullValue;

@RunWith(AndroidJUnit4.class)
@LargeTest
public class MyCoolActivityTests extends ActivityInstrumentationTestCase2<MyCoolActivity> {

    private MyCoolActivity mActivity;

    public MyCoolActivityTests() {
        super(MyCoolActivity.class);
    }

    @Before
    public void setUp() throws Exception {
        super.setUp();
        injectInstrumentation(InstrumentationRegistry.getInstrumentation());
        mActivity = getActivity();
    }

    @Test
    public void checkPreconditions() {
        assertThat(mActivity, notNullValue());
        // Check that Instrumentation was correctly injected in setUp()
        assertThat(getInstrumentation(), notNullValue());
    }

    @After
    public void tearDown() throws Exception {
        super.tearDown();
    }
}

I've added all necessary things to the build.gradle:

android {
    defaultConfig {
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
}

dependencies {
    androidTestCompile 'com.android.support.test.espresso:espresso-core:2.0'
    androidTestCompile 'com.android.support.test:testing-support-lib:0.1'
}

Is there any way to get this warning away?

Answer 1

ActivityInstrumentationTestCase2 is a JUnit 3 test case because it extends from TestCase.

@Test annotation is a replacement for the test-prefix naming convention used in JUnit 3. JUnit 4 test classes no longer require to extend TestCase or any of its subclasses. In fact JUnit 4 tests cannot extend TestCase, otherwise AndroidJUnitRunner will treat them as JUnit 3 tests.

http://developer.android.com/tools/testing-support-library/index.html#AndroidJUnitRunner

You could either migrate to ActivityTestRule provided by com.android.support.test:rules:0.4 (or later), or stick with JUnit 3.

Another option is InstrumentationRegistry, provided by Espresso 2, which has getInstrumentation(), getContext(), getTargetContext() (and more). These methods provide access to the current instrumentation, test context, and target context in a static manner. This makes it possible to write your own static utility methods for use in JUnit 4 test case classes. These utilities would mimic functionality that is currently only available in the base JUnit 3 test case classes. (This is no longer necessary.)