shadows/framework/src/main/java/org/robolectric/shadows/ShadowMediaPlayer.java
@Implementation
  protected void prepare() {
    checkStateException("prepare()", preparableStates);
    MediaInfo info = getMediaInfo();
    if (info.preparationDelay > 0) {
      SystemClock.sleep(info.preparationDelay);
    }
    invokePreparedListener();
  }
@Implementation
  protected void prepare() {
    checkStateException("prepare()", preparableStates);
    MediaInfo info = getMediaInfo();
    if (info.preparationDelay > 0) {
      SystemClock.sleep(info.preparationDelay);
    }
    invokePreparedListener();
  }
Simulates {@link MediaPlayer#prepareAsync()}. Sleeps for {@link MediaInfo#getPreparationDelay()
preparationDelay} ms by calling {@link SystemClock#sleep(long)} before calling {@link
#invokePreparedListener()}.

<p>If {@code preparationDelay} is not positive and non-zero, there is no sleep.

@see MediaInfo#setPreparationDelay(int)
@see #invokePreparedListener()