No tests found in <package> when testing with Espresso

Question

I want to test my MainActivity in my Android application. So, I created a first test case which tests the functionality of a button. If the user clicks this particular button, a new Activity should open.

Here is my code:

@RunWith(AndroidJUnit4.class)
public class MainActivityTest {

    @Rule
    public ActivityTestRule<MainActivity> mActivityRule = new ActivityTestRule<>(MainActivity.class);

    @Test
    public void startNewActivityTest() {
        Intents.init();
        onView(withId(R.id.main_new)).perform(click());
        intended(hasComponent(NewActivity.class.getName()));
        Intents.release();
    }

    @Before
    public void setup() {
        closeSoftKeyboard();
    }

}

Unfortunately, I get the following exception:

junit.framework.AssertionFailedError: No tests found in package.MainActivityTest
at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:191)
at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:176)
at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:554)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1701)

Here is my Gradle file:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 19
    buildToolsVersion "23.0.1"

    lintOptions {
        abortOnError false
    }

    defaultConfig {
        applicationId "package"
        minSdkVersion 14
        targetSdkVersion 19
    }

    signingConfigs {
        debug {
            storeFile file(RELEASE_STORE_FILE)
            storePassword RELEASE_STORE_PASSWORD
            keyAlias RELEASE_KEY_ALIAS
            keyPassword RELEASE_KEY_PASSWORD
        }
        release {
            storeFile file(RELEASE_STORE_FILE)
            storePassword RELEASE_STORE_PASSWORD
            keyAlias RELEASE_KEY_ALIAS
            keyPassword RELEASE_KEY_PASSWORD
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_7
        targetCompatibility JavaVersion.VERSION_1_7
    }
}

dependencies {
    compile 'com.android.support:support-v4:19.1.0'
    compile 'com.google.android.gms:play-services:4.2.+'
    androidTestCompile 'com.android.support:support-annotations:19.0.1'
    androidTestCompile 'com.android.support.test:runner:0.4.1'
    androidTestCompile 'com.android.support.test:rules:0.4.1'
    androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.1'
    // Set this dependency if you want to use Hamcrest matching
    androidTestCompile 'org.hamcrest:hamcrest-library:1.3'
    androidTestCompile 'com.android.support.test.espresso:espresso-intents:2.2.1'
}

Answer 1

Set the instrumentation runner

Add to the same build.gradle file the following line in android.defaultConfig: testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

apply plugin: 'com.android.application'

android {
    ...

    defaultConfig {
        ...

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

dependencies {
    // App's dependencies, including test
    compile 'com.android.support:support-annotations:23.0.1'

    ...
}

I never used Espresso Intents but perhaps you need this like here:

Use IntentsTestRule instead of ActivityTestRule when using Espresso-Intents. IntentsTestRule makes it easy to use Espresso-Intents APIs in functional UI tests. This class is an extension of ActivityTestRule, which initializes Espresso-Intents before each test annotated with @Test and releases Espresso-Intents after each test run. The activity will be terminated after each test and this rule can be used in the same way as ActivityTestRule.