Android Espresso Activity Clean Up

FinishingActivityTestRule.java

/**
 * Copyright (C) 2017 Drew Hannay
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package android.support.test.rule;

import android.app.Activity;
import android.support.test.runner.MonitoringInstrumentationAccessor;
import android.util.Log;

import java.lang.reflect.Field;

/**
 * Subclass of {@link ActivityTestRule} that cleanly handles finishing multiple activities.
 * <p/>
 * The official ActivityTestRule only calls finish() on the initial activity. However, this can cause problems if the
 * test ends in a different activity than which it was started. In this implementation, we call finish() on all
 * Activity classes that are started and wait until they actually finish before proceeding.
 */
public class FinishingActivityTestRule<T extends Activity> extends ActivityTestRule<T> {

    private static final String TAG = FinishingActivityTestRule.class.getSimpleName();

    public FinishingActivityTestRule(Class<T> activityClass) {
        super(activityClass);
    }

    public FinishingActivityTestRule(Class<T> activityClass, boolean initialTouchMode) {
        super(activityClass, initialTouchMode);
    }

    public FinishingActivityTestRule(Class<T> activityClass, boolean initialTouchMode, boolean launchActivity) {
        super(activityClass, initialTouchMode, launchActivity);
    }

    @Override
    void finishActivity() {
        MonitoringInstrumentationAccessor.finishAllActivities();

        // purposefully don't call super since we've already finished all the activities
        // instead, null out the mActivity field in the parent class using reflection
        try {
            Field activityField = ActivityTestRule.class.getDeclaredField("mActivity");
            activityField.setAccessible(true);
            activityField.set(this, null);
        } catch (NoSuchFieldException e) {
            Log.e(TAG, "Unable to get field through reflection", e);
        } catch (IllegalAccessException e) {
            Log.e(TAG, "Unable to get access field through reflection", e);
        }
    }
}

MonitoringInstrumentationAccessor.java

/**
 * Copyright (C) 2017 Drew Hannay
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package android.support.test.runner;

import android.os.Handler;
import android.os.Looper;
import android.support.test.InstrumentationRegistry;
import android.util.Log;

/**
 * Helper class for calling protected methods in MonitoringInstrumentation
 */
public class MonitoringInstrumentationAccessor {

    private static final String TAG = MonitoringInstrumentationAccessor.class.getSimpleName();

    private static final Handler HANDLER_FOR_MAIN_LOOPER = new Handler(Looper.getMainLooper());

    private MonitoringInstrumentationAccessor() {}

    /**
     * Synchronously finish all currently started activities
     */
    public static void finishAllActivities() {
        MonitoringInstrumentation instrumentation = (MonitoringInstrumentation) InstrumentationRegistry.getInstrumentation();
        MonitoringInstrumentation.ActivityFinisher activityFinisher = instrumentation.new ActivityFinisher();

        HANDLER_FOR_MAIN_LOOPER.post(activityFinisher);

        long startTime = System.currentTimeMillis();
        instrumentation.waitForActivitiesToComplete();
        long endTime = System.currentTimeMillis();
        Log.i(TAG, String.format("waitForActivitiesToComplete() took: %sms", endTime - startTime));
    }
}

It's better to mention that you should create packages android.support.test.runner and android.support.test.rule in your src/androidTest/java or src/androidTest/kotlin folder or you won't be able to access waitForActivitiesToComplete() method.