@Before
  public void setUp() {
    mFadeDrawable = new FakeFadeDrawable(mLayers);
    mFadeDrawable.setCallback(mCallback);
  }
Tests {@link FadeDrawable} where all layers are visible per default. * @see FadeDrawableTest for
more tests
drawee/src/test/java/com/facebook/drawee/drawable/FadeDrawableAllOnTest.java