public async Task GetDocumentTypesAsync_Valid_Test() { // Arrange _cityDocumentsService .Setup(c => c.GetAllCityDocumentTypesAsync()) .ReturnsAsync(It.IsAny <IEnumerable <CityDocumentTypeDTO> >()); CitiesController citycon = CreateCityController; // Act var result = await citycon.GetDocumentTypesAsync(); // Assert Assert.NotNull(result); Assert.IsInstanceOf <OkObjectResult>(result); }