如何为异步Web API编写单元测试

Question

I have a project in C# and Framework 6. I have a WEB API to call the methods. what is the best way to write a unit test for async WebAPI methods?

This is the method I have:

[HttpGet]
[Route("GetYears")]
public async Task<IEnumerable<Year>>  GetYears()
{
     IEnumerable<Year> newYears;    
     newYears = await creditApplicationsRepository.GetYearsAsync();
     return newYears;
}

Answer 1

You can use await to do this too.

[TestMethod]
public async Task GetYearsTest()
{
    //_sut is the System Under Test,  in this case is an instance of your controller
    var years = await _sut.GetYears();
    //Any Assert that you want
}

And to stub the return of the method creditApplicationsRepository.GetYearsAsync(); use this Task.FromResult(mockReturn) .

Answer 2

The key objective of a unit test is to test the functionality of the code inside a method. So async or not should not be particularly relevant functionally.

So I would say do something like this:

[TestMethod]
public void GetYearsTest(){
   //This would assume that your web api class has a mockable repository
   var yourClass = new YourClass(new MockRepository());

   //this is going to run your codes synchronously so you can get an immediate result to test on.
   var years = yourClass.GetYears().Result;

   //Run whatever test you want to on this
   Assert.IsNotNull(years);

}

If the purpose of running an Async test is to determine if your code is thread safe you will have to get creative to determine how to properly test your code to ensure it is in fact safe. In order for me to assist with that I would need to know more about the repo that is being used here or what variables could potentially get thread locked or result in an error.