How can I unit test an Android Activity that acts on Accelerometer?

Question

I am starting with an Activity based off of this ShakeActivity and I want to write some unit tests for it. I have written some small unit tests for Android activities befor

Answer 1

No need to test the OS's accelerometer, just test your own logic that responds to the OS - in other words your SensorListener. Unfortunately SensorEvent is private and I could not call SensorListener.onSensorChanged(SensorEvent event) directly, so had to first subclass SensorListener with my own class, and call my own method directly from the tests:

public  class ShakeDetector implements SensorEventListener {

     @Override
     public void onSensorChanged(SensorEvent event) {

         float x = event.values[0];
         float y = event.values[1];
         float z = event.values[2];

         onSensorUpdate(x, y, z);
     }

     public void onSensorUpdate(float x, float y, float z) {
         // do my (testable) logic here
     }
}

Then I can call onSensorUpdated directly from my test code, which simulates the accelerometer firing.

private void simulateShake(final float amplitude, int interval, int duration) throws InterruptedException {
    final SignInFragment.ShakeDetector shaker = getFragment().getShakeSensorForTesting();
    long start = System.currentTimeMillis();

    do {
        getInstrumentation().runOnMainSync(new Runnable() {
            @Override
            public void run() {
                shaker.onSensorUpdate(amplitude, amplitude, amplitude);
            }
        });
        Thread.sleep(interval);
    } while (System.currentTimeMillis() - start < duration);
}