public void RefreshSegmentNullChangesFetcherResponseShouldNotUpdateCache() { //Arrange var gates = new InMemoryReadinessGatesCache(); var apiClient = new Mock <ISegmentSdkApiClient>(); apiClient .Setup(x => x.FetchSegmentChanges(It.IsAny <string>(), It.IsAny <long>())) .Throws(new Exception()); var apiFetcher = new ApiSegmentChangeFetcher(apiClient.Object); var segments = new ConcurrentDictionary <string, Segment>(); var cache = new InMemorySegmentCache(segments); var segmentFetcher = new SelfRefreshingSegment("payed", apiFetcher, gates, cache); //Act segmentFetcher.RefreshSegment(); //Assert Assert.AreEqual(0, segments.Count); }