public async void ExecutePubmedQueryAndSaveRecords_Should() { //Arrange var mockWebClient = new Mock <IPubmedWebClient>(); var mockFileService = new Mock <IFileService>(); var mockUnitOfWork = new Mock <ILsUnitOfWork>(); mockWebClient .Setup(x => x.SubmitSearch("mice")) .Returns(Task.FromResult(new PubmedResultQueryDto { WebEnv = "env", QueryKey = "query", Count = 700 })); var sut = new PubmedService(mockWebClient.Object, mockFileService.Object, mockUnitOfWork.Object); //Act var result = sut.FindNewPubmedStudiesAndSave(Guid.Empty, Guid.Empty, "desctiption", Guid.Empty, "mice", 500); //Assert Assert.IsAssignableFrom <IAsyncEnumerable <PubmedXmlFileInfoDto> >(result); }