@Test
public void loadNativeAd_withNullResponseBody_shouldNotifyListenerOfOnNativeAdFailed() throws Exception {

    serverExtras.put(CustomEventNativeAdapter.RESPONSE_BODY_KEY, null);
    subject.loadNativeAd(context, mCustomEventNativeListener, localExtras, serverExtras);
    verify(mCustomEventNativeListener, never()).onNativeAdLoaded(any(MoPubCustomEventNative.MoPubForwardingNativeAd.class));
    verify(mCustomEventNativeListener).onNativeAdFailed(NativeErrorCode.UNSPECIFIED);
}