Ensure AnimatorTestRule timing is perfectly synchronized.

    private final Object mLock = new Object();

    private final TestHandler mTestHandler = new TestHandler();

    private final long mStartTime;

    private long mTotalTimeDelta = 0;

    /**

     * Construct an AnimatorTestRule with a custom start time.

     * @see #AnimatorTestRule()

     */

    public AnimatorTestRule(long startTime) {

        mStartTime = startTime;

    }

    /**

     * initializing the start time with {@link SystemClock#uptimeMillis()} reduces the discrepancies

     * with various internals of classes like ValueAnimator which can sometimes read that clock via

     * Construct an AnimatorTestRule with a start time of {@link SystemClock#uptimeMillis()}.

     * Initializing the start time with this clock reduces the discrepancies with various internals

     * of classes like ValueAnimator which can sometimes read that clock via

     * {@link android.view.animation.AnimationUtils#currentAnimationTimeMillis()}.

     */

    private final long mStartTime = SystemClock.uptimeMillis();

    private long mTotalTimeDelta = 0;

    public AnimatorTestRule() {

        this(SystemClock.uptimeMillis());

    }

    @NonNull

    @Override

 * advanced together.

 */

class AnimatorTestRule : TestRule {

    // Create the androidx rule, which initializes start time to SystemClock.uptimeMillis(),

    // then copy that time to the platform rule so that the two clocks are in sync.

    private val androidxRule = androidx.core.animation.AnimatorTestRule()

    private val platformRule = android.animation.AnimatorTestRule()

    private val platformRule = android.animation.AnimatorTestRule(androidxRule.startTime)

    private val advanceAndroidXTimeBy =

        Consumer<Long> { timeDelta -> androidxRule.advanceTimeBy(timeDelta) }

    /** Access the mStartTime field; bypassing the restriction of being on a looper thread. */

    private val androidx.core.animation.AnimatorTestRule.startTime: Long

        get() =

            javaClass.getDeclaredField("mStartTime").let { field ->

                field.isAccessible = true

                field.getLong(this)

            }

    /**

     * Chain is for simplicity not to force a particular order; order should not matter, because

     * each rule affects a different AnimationHandler classes, and no callbacks to code under test

        //  animation from one to start later than the other.

        platformRule.advanceTimeBy(timeDelta, advanceAndroidXTimeBy)

    }

    /**

     * Returns the current time in milliseconds tracked by the AnimationHandlers. Note that this is

     * a different time than the time tracked by {@link SystemClock}.

     */

    val currentTime: Long

        get() = androidxRule.currentTime

}