    @Test
    public void testRemove() throws Exception {

        RxCache underlyingCache = mock(RxCache.class);

        LazyExpirableCache lazyExpirableCache = LazyExpirableCache.fromCache(underlyingCache, 10, TimeUnit.SECONDS,
                simpleTimeProvider);

        String cacheKey = "cache_key";

        when(underlyingCache.remove(eq(cacheKey))).thenReturn(Observable.just(true));

        Observable<Boolean> observable = lazyExpirableCache.remove(cacheKey);
        ObservableTestUtils.testObservable(observable, Assert::assertTrue);

        verify(underlyingCache).remove(cacheKey);
    }