### Question:
MemoryStoreCore implements StoreCoreInterface<T, U> { @NonNull @Override public Single<Boolean> delete(@NonNull final T id) { return Single.fromCallable(() -> cache.remove(getHashCodeForId(id)) != null); } MemoryStoreCore();  MemoryStoreCore(@NonNull final BiFunction<U, U, U> putMergeFunction); @NonNull @Override Maybe<U> getCached(@NonNull final T id); @NonNull @Override Single<List<U>> getCached(); @NonNull @Override Observable<U> getStream(@NonNull final T id); @NonNull @Override Observable<U> getStream(); @NonNull @Override Single<Boolean> put(@NonNull final T id, @NonNull final U item); @NonNull @Override Single<Boolean> delete(@NonNull final T id);  }### Answer:
@Test public void delete_WithNoExistingValue_EmitsFalse() { memoryStoreCore.delete(100) .test() .assertComplete() .assertValue(false); }