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How to write unit tests for asp.net core web api controller

So I am very new to writing tests. I created an ASP.NET core web api along with angular. I have to write unit tests for the web API controllers. I have been reading Microsoft documentation on how to get started with unit tests of ASP.NET web APIs. But I am still very unsure on how to go about writing proper tests.
My Controller Code
[Authorize]
[Route("api/[controller]")]
[ApiController]
public class OrdersController : ControllerBase
{
private readonly IOrderRepository _repo;
private readonly IMapper _mapper;
public OrdersController(IOrderRepository repo, IMapper mapper)
{
_repo = repo;
_mapper = mapper;
}
[AllowAnonymous]
[HttpPost()]
public async Task<IActionResult> AddOrder(OrderForMappingDto orderForMappingDto)
{
//if(orderForMappingDto.ARentalOrNot == null)
//{
// throw new Exception("Value can't be left null");
//}
var orderToCreate = _mapper.Map<TblOrder>(orderForMappingDto);
var createdOrder = await _repo.AddOrder(orderToCreate);
return Ok(createdOrder);
}
}
My Repository Code
public class OrderRepository : IOrderRepository
{
private readonly MovieRentalDBContext _context;
public OrderRepository(MovieRentalDBContext context)
{
_context = context;
}
public async Task<TblOrder> AddOrder(TblOrder tblOrder)
{
await _context.TblOrder.AddAsync(tblOrder);
await _context.SaveChangesAsync();
return tblOrder;
}
}
I understand there is a lot of mocking to be done. But do I need to mock the Entity Framework as well?
I wrote a simple test file.
public void PostsAorder_WhenCalled_ReturnsOkWithResponse()
{
var mockOrderRepository = new Mock<IOrderRepository>();
var mockOrderMapper = new Mock<IMapper>();
var orderControllerObject = new OrdersController(mockOrderRepository.Object, mockOrderMapper.Object);
Task<IActionResult> contentResult = orderControllerObject.AddOrder(new OrderForMappingDto
{
ACustomerId = 3,
AMovieId = 18,
ARentalOrNot = false,
AOrderedDate = DateTime.Now
}) ;
//var contentResult = actionResult as OkNegotiatedContentResult<OrderForMappingDto>;
Assert.IsNotNull(contentResult);
Assert.IsNotNull(contentResult.Result);
}
The OkNegotioatedContent function doesn't work with Tasks. How do I go about using that for task. Also, the tests is passing even when I don't supply the last 3 arguments even though in the DTO they are classified as [Required]. Can somebody help on how to modify the test properly.
mapper Configuration-

Your test is almost okay. First the fixed version then some explanation:
[Fact]
public async Task GivenAValidOrder_WhenICallTheAsOrder_ThenItReturnsOkWithResponse()
{
//Arrange
var mockOrderMapper = new Mock<IMapper>();
mockOrderMapper.Setup(mapper => mapper.Map<TblOrder>(It.IsAny<OrderForMappingDto>()))
.Returns(new TblOrder());
var mockOrderRepository = new Mock<IOrderRepository>();
mockOrderRepository.Setup(repo => repo.AddOrder(It.IsAny<TblOrder>()))
.ReturnsAsync((TblOrder order) => order);
var SUT = new OrdersController(mockOrderRepository.Object, mockOrderMapper.Object);
//Act
var contentResult = await SUT.AddOrder(new OrderForMappingDto
{
ACustomerId = 3,
AMovieId = 18,
ARentalOrNot = false,
AOrderedDate = DateTime.Now
});
//Assert
Assert.NotNull(contentResult);
Assert.IsAssignableFrom<OkObjectResult>(contentResult);
var result = ((OkObjectResult)contentResult).Value;
Assert.NotNull(result);
Assert.IsAssignableFrom<TblOrder>(result);
}
The name of test follows the Given When Then structure to make it easier to understand that under what circumstances how should the controller's action behave.
The test is now asynchronous because we need to await the controller's action to finish in order to examine its result.
I've added the Arrange Act Assert comments to the code in order to emphasize which phase starts when.
I've set the mapper mock to return a new TblOrder and the repo mock to return whatever it receives.
I've renamed orderControllerObject to SUT, because it emphasize which component is under examination (System Under Test).
In the result verification I've used IsAssingableForm instead of IsType because it checks against derived classes as well. In this particular case it is not mandatory, but it is a good practice.
The result type will be OkObjectResult not OkNegotiatedContentResult, so you should check against that.
And finally I've added an extra check to make sure that the returned object's type is that what is expected.

How can I use Moq here?

My WEB API project is using a Generic Repository that implements an interface like this:
public interface IGenericEFRepository<TEntity> where TEntity : class
{
Task<IEnumerable<TEntity>> Get();
Task<TEntity> Get(int id);
}
public class GenericEFRepository<TEntity> : IGenericEFRepository<TEntity>
where TEntity : class
{
private SqlDbContext _db;
public GenericEFRepository(SqlDbContext db)
{
_db = db;
}
public async Task<IEnumerable<TEntity>> Get()
{
return await Task.FromResult(_db.Set<TEntity>());
}
public async Task<TEntity> Get(int id)
{
var entity = await Task.FromResult(_db.Set<TEntity>().Find(new object[] { id }));
if (entity != null && includeRelatedEntities)
{
//Some Code
}
return entity;
}
}
Well now I want to test this service. for this I have used the following code:
public class CustomerControllerTest
{
CustomerController _controller;
ICustomerProvider _provider;
ICustomerInquiryMockRepository _repo;
public CustomerControllerTest()
{
_repo = new CustomerInquiryMockRepository();
_provider = new CustomerProvider(_repo);
_controller = new CustomerController(_provider);
}
[Fact]
public async Task Get_WhenCalled_ReturnsOkResult()
{
// Act
var okResult = await _controller.Get();
// Assert
Assert.IsType<OkObjectResult>(okResult);
}
[Fact]
public async Task GetById_UnknownCustomerIdPassed_ReturnsNotFoundResult()
{
// Act
var notFoundResult = await _controller.Get(4);
// Assert
Assert.IsType<NotFoundResult>(notFoundResult);
}
}
Which my tests are working fine by creating a fake non-generic service manually with mock data (In-Memory) like below, instead of using my real generic interface and it's implementation that uses my database as data-source:
public interface ICustomerInquiryMockRepository
{
Task<IEnumerable<CustomerDTO>> GetCustomers();
Task<CustomerDTO> GetCustomer(int customerId);
}
And it's implementation:
public class CustomerInquiryMockRepository : ICustomerInquiryMockRepository
{
public async Task<IEnumerable<CustomerDTO>> GetCustomers()
{
return await Task.FromResult(MockData.Current.Customers);
}
public async Task<CustomerDTO> GetCustomer(int CustomerId)
{
var Customer = await Task.FromResult(MockData.Current.Customers.FirstOrDefault(p => p.CustomerID.Equals(CustomerId)));
if (includeTransactions && Customer != null)
{
Customer.Transactions = MockData.Current.Transactions.Where(b => b.CustomerId.Equals(CustomerId)).ToList();
}
return Customer;
}
}
And the MockData.Current.Customers is just a simple fake (In-Memory) List of Customers. Long story short, the above tests are working fine, however I am feeling I have repeated my self a lot and so I have decided to use Moq library instead of creating fake service manually. For this purpose I have used Moq like this:
public class CustomerControllerTest
{
CustomerController _controller;
ICustomerProvider _provider;
//ICustomerInquiryMockRepository _repo;
Mock<ICustomerInquiryMockRepository> mockUserRepo;
public CustomerControllerTest()
{
mockUserRepo = new Mock<ICustomerInquiryMockRepository>();
//_repo = new CustomerInquiryMockRepository();
_provider = new CustomerProvider(mockUserRepo.Object);
_controller = new CustomerController(_provider);
}
[Fact]
public async Task Get_WhenCalled_ReturnsOkResult()
{
mockUserRepo.Setup(m => m.GetCustomers())
.Returns(Task.FromResult(MockData.Current.Customers.AsEnumerable()));
// Act
var okResult = await _controller.Get();
// Assert
Assert.IsType<OkObjectResult>(okResult);
}
[Fact]
public async Task GetById_UnknownCustomerIdPassed_ReturnsNotFoundResult()
{
//Arrange
I don't know how can I use Moq here and in the other parts of my tests
// Act
var notFoundResult = await _controller.Get(4);
// Assert
Assert.IsType<NotFoundResult>(notFoundResult);
}
Now my question is the Mock is working fine when I use it for Mocking the GetCustomers method because I simply paste the code from GetCustomers method in the CustomerInquiryMockRepository in the Returns method of the Mock object. However I don't really have any idea how can I use Mock for my other methods inside this Repository. Should I replace anything that I have in the Return method?

You can mock out your repository like so:
var mockUserRepo = new Mock<ICustomerInquiryMockRepository>();
mockUserRepo.Setup(x => x.GetCustomers())
.Returns(Task.FromResult(MockData.Current.Customers.AsEnumerable());
mockUserRepo.Setup(x => x.GetCustomer(It.IsAny<int>()))
.Returns(res => Task.FromResult(MockData.Current.Customers.ElementAt(res));
If you want to mock out specific values for GetCustomer, you can do:
mockUserRepo.Setup(x => x.GetCustomer(It.Is<int>(y => y == 4)))
.Returns(res => Task.FromResult(/* error value here */));
I think the key here is to use It.Is or It.IsAny based on how you want to mock out the object. Generally, you also want to mock out interfaces that are used in production code, instead of having production code depend on something with Mock or Test in the name. I would recommend against taking a production code dependency on something named ICustomerInquiryMockRepository, if that is indeed what you're doing and not just part of the MCVE you've provided.
Tests usually use mocking to test the workflow of an application at a high level, so you would usually want to mock out your services level, call a controller, and verify that the services were called as expected. For example:
// Production class sample
class ProductionController
{
public ProductionController(IService1 service1, IService2 service2) { }
public void ControllerMethod()
{
var service1Result = service1.Method();
service2.Method(service1Result);
}
}
// Test sample
// arrange
var expectedResult = new Service1Result();
var service1 = Mock.Of<IService1>(x => x.Method() == expectedResult);
var service2 = Mock.Of<IService2>(x => x.Method(It.Is<Service1Result>(y => y == expectedResult)));
var controller = new ProductionController(service1, service2);
// act
controller.ControllerMethod();
// assert
Mock.Get(service1).Verify(x => x.Method(), Times.Once);
Mock.Get(service2).Verify(x => x.Method(expectedResult), Times.Once);
As you can see from the example, you aren't checking the business logic of either of the services, you're just validating that the methods were called with the expected data. The test is built around verification of methods being called, not any particular branching logic.
Also, unrelated to your question, Moq also has a cool syntax you can use for simple mock setups:
var repo = Mock.Of<ICustomerInquiryMockRepository>(x =>
x.GetCustomers() == Task.FromResult(MockData.Current.Customers.AsEnumerable()));
You can use Mock.Get(repo) if you need to do additional setup on the repository. It's definitely worth checking out, I find it much nicer to read.

How to properly moq ExecuteQuery method within DataContext?

I'm having a difficult time trying to understand how to appropriately return mocked data from a simulated database call in a unit test.
Here's an example method I want to unit test (GetBuildings):
public class BuildingService : IBuildingService {
public IQueryable<Building> GetBuildings(int propertyId)
{
IQueryable<Building> buildings;
// Execution path for potential exception thrown
// if (...) throw new SpecialException();
// Another execution path...
// if (...) ...
using (var context = DataContext.Instance())
{
var Params = new List<SqlParameter>
{
new SqlParameter("#PropertyId", propertyId)
};
// I need to return mocked data here...
buildings = context
.ExecuteQuery<Building>(System.Data.CommandType.StoredProcedure, "dbo.Building_List", Params.ToArray<object>())
.AsQueryable();
}
return buildings;
}
}
So GetBuildings calls a stored procedure.
So I need to mock the DataContext, that of which I can override and set a testable instance. So what happens here is, in the above example DataContext.Instance() does return the mocked object.
[TestFixture]
public class BuildingServiceTests
{
private Mock<IDataContext> _mockDataContext;
[SetUp]
public void Setup() {
_mockDataContext = new Mock<IDataContext>();
}
[TearDown]
public void TearDown() {
...
}
[Test]
public void SomeTestName() {
_mockDataContext.Setup(r =>
r.ExecuteQuery<Building>(CommandType.StoredProcedure, "someSproc"))
.Returns(new List<Building>() { new Building() { BuildingId = 1, Title = "1" }}.AsQueryable());
DataContext.SetTestableInstance(_mockDataContext.Object);
var builings = BuildingService.GetBuildings(1, 1);
// Assert...
}
Please ignore some of the parameters, like propertyId. I've stripped those out and simplified this all. I simply can't get the ExecuteQuery method to return any data.
All other simple peta-poco type methods I can mock without issue (i.e. Get, Insert, Delete).
Update
DataContext.Instance returns the active instance of the DataContext class, if exists, and if not exists, returns a new one. So the method of test under question returns the mocked instance.

Do not mock DataContext. Because mocking DataContext will produce tests tightly coupled to the implementation details of DataContext. And you will be forced to change tests for every change in the code even behavior will remain same.
Instead introduce a "DataService" interface and mock it in the tests for BuildingService.
public interface IDataService
{
IEnumerable<Building> GetBuildings(int propertyId)
}
Then, you can tests implementation of IDataService agains real database as part of integration tests or tests it agains database in memory.
If you can test with "InMemory" database (EF Core or Sqlite) - then even better -> write tests for BuildingService against actual implementation of DataContext.
In tests you should mock only external resources (web service, file system or database) or only resources which makes tests slow.
Not mocking other dependencies will save you time and give freedom while you refactoring your codebase.
After update:
Based on the updated question, where BuildingService have some execution path - you can still testing BuildingService and abstract data related logic to the IDataService.
For example below is BuildingService class
public class BuildingService
{
private readonly IDataService _dataService;
public BuildingService(IDataService dataService)
{
_dataService = dataService;
}
public IEnumerable<Building> GetBuildings(int propertyId)
{
if (propertyId < 0)
{
throw new ArgumentException("Negative id not allowed");
}
if (propertyId == 0)
{
return Enumerable.Empty<Building>();
}
return _myDataService.GetBuildingsOfProperty(int propertyId);
}
}
In tests you will create a mock for IDataService and pass it to the constructor of BuildingService
var fakeDataService = new Mock<IDataContext>();
var serviceUnderTest = new BuildingService(fakeDataService);
Then you will have tests for:
"Should throw exception when property Id is negative"
"Should return empty collection when property Id equals zero"
"Should return collection of expected buildings when valid property Id is given"
For last test case you will mock IDataService to return expected building only when correct propertyId is given to _dataService.GetBuildingsOfProperty method

In order for the mock to return data is needs to be set up to behave as expected given a provided input.
currently in the method under test it is being called like this
buildings = context
.ExecuteQuery<Building>(System.Data.CommandType.StoredProcedure, "dbo.Building_List", Params.ToArray<object>())
.AsQueryable();
Yet in the test the mock context is being setup like
_mockDataContext.Setup(r =>
r.ExecuteQuery<Building>(CommandType.StoredProcedure, "someSproc"))
.Returns(new List<Building>() { new Building() { BuildingId = 1, Title = "1" }}.AsQueryable());
Note what the mock is told to expect as parameters.
The mock will only behave as expected when provided with those parameters. Otherwise it will return null.
Consider the following example of how the test can be exercised based on the code provided in the original question.
[Test]
public void SomeTestName() {
//Arrange
var expected = new List<Building>() { new Building() { BuildingId = 1, Title = "1" }}.AsQueryable();
_mockDataContext
.Setup(_ => _.ExecuteQuery<Building>(CommandType.StoredProcedure, It.IsAny<string>(), It.IsAny<object[]>()))
.Returns(expected);
DataContext.SetTestableInstance(_mockDataContext.Object);
var subject = new BuildingService();
//Act
var actual = subject.GetBuildings(1);
// Assert...
CollectionAssert.AreEquivalent(expected, actual);
}
That said, the current design of the system under test is tightly coupled to a static dependency which is a code smell and makes the current design follow some bad practices.
The static DataContext which is currently being used as a factory should be refactored as such,
public interface IDataContextFactory {
IDataContext CreateInstance();
}
and explicitly injected into dependent classes instead of calling the static factory method
public class BuildingService : IBuildingService {
private readonly IDataContextFactory factory;
public BuildingService(IDataContextFactory factory) {
this.factory = factory
}
public IQueryable<Building> GetBuildings(int propertyId) {
IQueryable<Building> buildings;
using (var context = factory.CreateInstance()) {
var Params = new List<SqlParameter> {
new SqlParameter("#PropertyId", propertyId)
};
buildings = context
.ExecuteQuery<Building>(System.Data.CommandType.StoredProcedure, "dbo.Building_List", Params.ToArray<object>())
.AsQueryable();
}
return buildings;
}
}
This will allow for a proper mock to be created in injected into the subject under test without using a static workaround hack.
[Test]
public void SomeTestName() {
//Arrange
var expected = new List<Building>() { new Building() { BuildingId = 1, Title = "1" }}.AsQueryable();
_mockDataContext
.Setup(_ => _.ExecuteQuery<Building>(CommandType.StoredProcedure, It.IsAny<string>(), It.IsAny<object[]>()))
.Returns(expected);
var factoryMock = new Mock<IDataContextFactory>();
factoryMock
.Setup(_ => _.CreateInstance())
.Returns(_mockDataContext.Object);
var subject = new BuildingService(factoryMock.Object);
//Act
var actual = subject.GetBuildings(1);
// Assert...
CollectionAssert.AreEquivalent(expected, actual);
}

When to return IHttpActionResult vs Object

In examples of using the ASP.NET Web API I see two different methods used to return data to the calling jQuery function. The first method returns an object of type Client but I am not sure what the second method is returning.
Method #1 (returns Client object)
public IEnumerable<Client> GetAllClients()
{
using (var context = new PQRSModel.PQRSEntities())
{
context.Configuration.ProxyCreationEnabled = false;
var query = context.Clients.OrderBy(c = c.OrgName);
var customers = query.ToList();
return customers;
}
}
Method #2 (What benefit does IHttpActionResult provide?)
public IHttpActionResult GetClient(int clientId)
{
using (var context = new PQRSModel.PQRSEntities())
{
context.Configuration.ProxyCreationEnabled = false;
var client = context.Clients.FirstOrDefault(c = c.ID == clientId);
if (client == null)
{
return NotFound();
}
return Ok(client);
}
}
If the second method finds a single object is there any reason it could not also return a Client object type?

Returning IHttpActionResult provides a nice separation of concerns.
Your controller can focus on responding to the request in the most sensible manner (status codes, error messages, etc.). Another (service) layer can focus on actually retrieving and transforming the business data.
The side-effect is, your controller methods become more unit testable. Consider the following simple example:
public class MyController : ApiController
{
//or better yet, dependency-inject this
SomeService _service = new SomeService();
public IHttpActionResult Get(int id)
{
if (id < 0)
return BadRequest("Some error message");
var data = _service.GetData(id);
if (data == null)
return NotFound();
return Ok(data);
}
}
Not only is this method's logic understandable just by reading it, but you could now test the logic more easily and naturally, something like (using NUnit syntax):
[TestFixture]
public class MyControllerTests
{
[Test]
public void Get_WithIdLessThan0_ReturnsBadRequest()
{
var controller = new MyController();
int id = -1;
IHttpActionResult actionResult = controller.Get(id);
Assert.IsInstanceOf<BadRequestErrorMessageResult>(actionResult);
}
}
Similarly, you could mock the Service layer and test what happens when you give known id parameters to the controller, etc.
Here is a good article on Unit Testing Controllers in Web Api

The second method allows you to return just status codes (like the 404 in the example), streaming file content and other types of non-object content.

call another api controller

When I call user controller (api/user), I am able to pass user credentials, however the application crashes with null exception error (Value cannot be null) in the values controller:
public class ValuesController : ApiController
{
private cdwEntities db = new cdwEntities();
public HttpResponseMessage Get([FromUri] Query query)
{
var data = db.database.AsQueryable();
if (query.name != null)
{
data = data.Where(c => c.Name == query.name);
}
if (query.price != null)
{
data = data.Where(c => c.Price == query.price);
}
if (!data.Any())
{
var message = string.Format("error");
return Request.CreateErrorResponse(HttpStatusCode.NotFound, message);
}
***return Request.CreateResponse(HttpStatusCode.OK, data);***
}
}
I believe this error is because valuescontroller method cannot pass null values as it always pass parameters(i.e. api/values/name=tom), hence when I call user controller, it throws null error because the system has not passed any parameters into the Valuescontroller from user controller.
public class UserController : ApiController
{
[Authorize]
public HttpResponseMessage Get([FromUri] Query query)
{
if (User.IsInRole("user"))
{
var result = new itemController();
return result.Get(query);
}
var message = string.Format("No data was found");
return Request.CreateErrorResponse(HttpStatusCode.NotFound, message);
}
}
Is their some built-in function i could use to solve this issue or any framework/library i should look into?
Many thanks for your help and time.

Others have pointed out that you should not often (ever?) call one view controller endpoint from another, but in the case that you need/want to, you need to be sure the target has been initialized properly. This is done using ControllerBuilder.
So instead of:
var result = new itemController();
return result.Get(query); // this will blow up!
You would do:
IControllerFactory factory = ControllerBuilder.Current.GetControllerFactory();
itemController c = (itemController) factory.CreateController(
ControllerContext.RequestContext, "item");
return c.Get(query);
This will ensure that the target view controller has been initialized with all necessary context.

You should not call one API endpoint method from other API endpoint. Instead you need to have proper segregation of code between API, Business Logic Layer and Data Access Layer. I would do it in following way -
API -
public class UserController : ApiController
{
[Authorize]
public HttpResponseMessage Get([FromUri] Query query)
{
BusinessLayer layer = new BusinessLayer();
if (User.IsInRole("user"))
{
var result = layer.GetData(query);
// use result here and return HttpResponseMessage
var message = string.Format("No data was found");
return Request.CreateErrorResponse(HttpStatusCode.NotFound, message);
}
}
}
And in your business logic layer -
public ResultModel Get(Query query)
{
// Process your model Query here... and then return some meaningful result here...
// Also call Data Access Layer Methods from here, instead of making direct database
// (entity framework) calls...
}
For better flexible and loosely coupled systems, you need to have Dependency Injection (probably using Unity, but there are many other options like Autofac, Ninject etc.)