public async Task GetFileBase64_Valid_Test() { // Arrange _cityDocumentsService .Setup(c => c.DownloadFileAsync(It.IsAny <string>())) .ReturnsAsync(It.IsAny <string>()); CitiesController citycon = CreateCityController; _cityParticipantsService.Setup(c => c.RemoveAdministratorAsync(It.IsAny <int>())); // Act var result = await citycon.GetFileBase64(GetFakeFileName()); // Assert Assert.NotNull(result); Assert.IsInstanceOf <OkObjectResult>(result); }