How to write test code for Web API in Visual Studio? - visual-studio

Question

I'm a bit new to test project. I currently have a web api project which contains Get, Put, Post and Delete methods. When comes to writing test cases, I'm confused. Should I write test code to test the Http URL?
My web api code:
// GET api/values/5
[HttpGet("{id}")]
public IActionResult Get(string id)
{
using (var unitOfWork = new UnitOfWork(_db))
{
var r = unitOfWork.Resources.Get(id);
unitOfWork.Complete();
Models.resource result = ConvertResourceFromCoreToApi(r);
if (result == null)
{
return NotFound();
}
else
{
return Ok(result);
}
}
}
And in my test project, I kind of stuck here. We are using Xunit. How to write test code to test the Get method? Or should I write code to test the URL api/values/5 instead, but how?
[Fact]
public void GetTest()
{
using (var unitOfWork = new UnitOfWork(new MockDatabase()))
{
}
}
Any help would be appreciated.

Answer 1

You need to make a couple of changes before you can really unit test your controller. You need to pass an instance of your UnitOfWork class into the controller in its constructor. Then your controller method code becomes:
// GET api/values/5
[HttpGet("{id}")]
public IActionResult Get(string id)
{
var r = unitOfWork.Resources.Get(id);
unitOfWork.Complete();
Models.resource result = ConvertResourceFromCoreToApi(r);
if (result == null)
{
return NotFound();
}
else
{
return Ok(result);
}
Then in your unit tests you do this:
[Fact]
public void GetTest()
{
// Arrange
// You really want to mock your unit of work so you can determine
// what you are going to send back
var unitOfWork = new MockUnitOfWork();
var systemUnderTest = new Controller(unitOfWork);
system.Request = new HttpRequestMessage();
// Act
var result = systemUnderTest.Get(1);
// Assert
// Here you need to verify that you got back the expected result
}
Injecting the UnitOfWork class into the controller is probably another question. Mark Seemann has an excellent post on the subject, but it might be a little advanced. There are a number of different ways to accomplish that with simpler (but maybe not as robust methods). Google is your friend with that. But if you have questions, post another question.
Hope that helps.

Answer 2

You would need to make some design changes to your controller to make it easy to test. In your action you are creating an instances which will make it difficult to test with a fake dependencies to the controller. Also your controller should depend on abstractions rather than concretions which will allow the controller to be more testable.
public class MyWebApiController : ApiController {
private IUnitOfWork unitOfWork;
public MyWebApiController(IUnitOfWork unitOfWork) {
this.unitOfWork = unitOfWork;
}
// GET api/values/5
[HttpGet("{id}")]
public IActionResult Get(string id) {
var r = unitOfWork.Resources.Get(id);
unitOfWork.Complete();
Models.resource result = ConvertResourceFromCoreToApi(r);
if (result == null) {
return NotFound();
} else {
return Ok(result);
}
}
//...other code
}
Notice the controller uses dependency injection to inject an IUnitOfWork. That makes the controller more testable, because you can inject mocks of its dependencies when unit testing.
From there it is just to create an instance of the controller and call the method under test with mocks of the dependencies.
[Fact]
public void GetTest() {
//Arrange (Setup the parts needed to run test)
var unitOfWork = new MockUnitOfWork(new MockDatabase());
//Or using your mocking framework of choice
//var unitOfWork = Mock.Of<IUnitOfWork>(); //this is using Moq
var controller = new MyWebApiController(unitOfWork);
var id = "Test Id value here";
//Act (call the method under test)
var result - controller.Get(id);
//Assert (check results)
//...Do your assertion pertaining to result of calling method under test
}
Reference : Unit Testing Controllers in ASP.NET Web API 2