DrawableMatcher for medium article https://is.gd/Ru0XVF

DrawableMatcher.java

public class DrawableMatcher extends TypeSafeMatcher<View> {

    private final int expectedId;
    private String resourceName;
    private int isAnimatedDrawable = -1;

    private int randomFrame = 0;

    public DrawableMatcher(int expectedId) {
        super(View.class);
        this.expectedId = expectedId;
    }
    public DrawableMatcher(int expectedId, int isAnimatedDrawable) {
        super(View.class);
        this.expectedId = expectedId;
        this.isAnimatedDrawable = isAnimatedDrawable;
    }

    @Override
    protected boolean matchesSafely(View target) {
        boolean result = false;

        Resources resources = target.getContext().getResources();
        resourceName = resources.getResourceEntryName(expectedId);

        Bitmap objectBitmap = null;
        Bitmap expectedBitmap = null;

        Random random = new Random();

        //if it's imageView
        if (target instanceof ImageView) {
            ImageView imageView = (ImageView) target;
            if (expectedId < 0) {
                return imageView.getDrawable() == null;
            }

            if (isAnimatedDrawable != DrawableUtils.ANIMATED_DRAWABLE) {
                Drawable expectedDrawable = resources.getDrawable(expectedId);
                if (expectedDrawable == null) {
                    return false;
                }
                objectBitmap = ((BitmapDrawable) imageView.getDrawable()).getBitmap();
                expectedBitmap = ((BitmapDrawable) expectedDrawable).getBitmap();
                result = objectBitmap.sameAs(expectedBitmap);
            } else {
                AnimationDrawable expectedDrawable = (AnimationDrawable) resources.getDrawable(expectedId);
                if (expectedDrawable == null) {
                    return false;
                }

                //get a random frame
                randomFrame = random.nextInt(expectedDrawable.getNumberOfFrames());

                AnimationDrawable objectAnimationDrawable = ((AnimationDrawable) imageView.getDrawable());
                Drawable drawable0 = objectAnimationDrawable.getFrame(randomFrame);
                objectBitmap = ((BitmapDrawable) drawable0).getBitmap();

                Drawable drawable1 = expectedDrawable.getFrame(randomFrame);
                expectedBitmap = ((BitmapDrawable) drawable1).getBitmap();

                result = objectBitmap.sameAs(expectedBitmap);
            }

        }


        //if it's Button
        else if (target instanceof Button) {
            Button button = (Button) target;

            if (isAnimatedDrawable == DrawableUtils.ANIMATED_DRAWABLE) {
                AnimationDrawable expectedDrawable = (AnimationDrawable) resources.getDrawable(expectedId);

                if (expectedDrawable == null) {
                    return false;
                }

                randomFrame = random.nextInt(expectedDrawable.getNumberOfFrames());

                Drawable drawable0 = expectedDrawable.getFrame(randomFrame);
                AnimationDrawable buttonBackground = ((AnimationDrawable) button.getBackground());
                Drawable drawable1 = buttonBackground.getFrame(randomFrame);

                objectBitmap = ((BitmapDrawable) drawable0).getBitmap();
                expectedBitmap = ((BitmapDrawable) drawable1).getBitmap();

                // if (buttonBackground.isRunning())
                result = objectBitmap.sameAs(expectedBitmap);
            }
        }

        return result;
    }


    @Override
    public void describeTo(Description description) {
        description.appendText("with drawable from resource id: ");
        description.appendValue(expectedId);
        if(isAnimatedDrawable == DrawableUtils.ANIMATED_DRAWABLE){
        description.appendText("frame chosen for matching: ");
        description.appendValue(randomFrame);
        }      
        if (resourceName != null) {
            description.appendText("[");
            description.appendText(resourceName);
            description.appendText("]");
        }
    }
}