public async void GetDocuments_ShouldCallService() { // Arrange _mockService.Setup(_ => _.GetDocuments(It.IsAny <string>())) .ReturnsAsync(It.IsAny <List <CouncilTaxDocumentReference> >()); // Act var result = await _controller.GetDocuments(It.IsAny <string>()); // Assert _mockService.Verify(_ => _.GetDocuments(It.IsAny <string>()), Times.Once); var actionResult = Assert.IsType <OkObjectResult>(result); Assert.Equal(200, actionResult.StatusCode); }