@Test(expected = IllegalArgumentException.class)
public void observeNetworkConnectivityShouldThrowAnExceptionForNullContext() {

  // given
  final Context context = null;
  final NetworkObservingStrategy strategy = new LollipopNetworkObservingStrategy();
  // when
  ReactiveNetwork.observeNetworkConnectivity(context, strategy);
  // then an exception is thrown
}