private void assertShowsCustomEventInterstitial(boolean shouldBeReady) {
    MoPubInterstitial.MoPubInterstitialView moPubInterstitialView =
        subject.new MoPubInterstitialView(activity);
    moPubInterstitialView.loadCustomEvent(customEventClassName, serverExtras);

    assertThat(subject.isReady()).isEqualTo(shouldBeReady);
    assertThat(subject.show()).isEqualTo(shouldBeReady);

    if (shouldBeReady) {
      verify(customEventInterstitialAdapter).showInterstitial();
    } else {
      verify(customEventInterstitialAdapter, never()).showInterstitial();
    }
  }