Android Studio Espresso Testing Error: Empty Test Suite

I keep running into the following error when trying to execute my tests in Android Studio: Test running failed: Unable to find instrumentation info for: ComponentInfo{.test/android.support.test.runner.AndroidJUnitRunner}

My test class is in the androidTest/java directory and has a constructor. My build.gradle is correct too. Any help is appreciated.

Test Class

@RunWith(AndroidJUnit4.class)
@LargeTest
public class AndroidUITests extends ActivityInstrumentationTestCase2<UserActivity>{

    private UserActivity userActivity;

    public AndroidUITests() {
        super(UserActivity.class);
    }


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

    @Test
    public void testPhoneIconIsDisplayed() {
        // When the phone_icon view is available,
        // check that it is displayed.
        onView(ViewMatchers.withId(R.id.groupCreate)).perform(click())
                .check(matches(withText("Enter a name")));
    }
}

app/build.gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion "21.1.2"

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

    packagingOptions {
        exclude 'LICENSE.txt'
    }
}

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