@Test
public void testWithRoll180() {

  tracker.onOrientationChange(dummyMatrix, (float) Math.toRadians(180));
  // X-axis should now control reverse yaw.
  swipe(tracker, 0, 0, -2 * SWIPE_PX, 0);
  assertThat(yaw).isWithin(EPSILON).of(-2 * SWIPE_PX / PX_PER_DEGREES);
  // Y-axis should now control reverse pitch.
  swipe(tracker, 0, 0, 0, -3 * SWIPE_PX);
  assertThat(pitch).isWithin(EPSILON).of(3 * SWIPE_PX / PX_PER_DEGREES);
}