Question

I have a a fairly significant dependency graph for an object I want to test. What is the easiest way to resolve my dependencies without having to register mocks everywhere?

For example, I have a dependency graph like this:

  PublicApi
    ApiService
      AccountingFacade
         BillingService
           BillingValidation
           BillingRepository
         UserService
           UserRepository

I want to test PublicApi.CreateUser(), and I want it to run through all the code, but I want to mock the repositories so I don’t have to write anything to the database. Should I just use a DI container and register all my services, replacing the repositories with mocks, then resolve PublicApi and run the method?

I was looking into AutoFixture, and it looks like it might be able to handle something like this, but I can’t quite wrap my head around the whole ‘Freeze’ vs ‘Register’ and it’s integration with Moq.

Answer 1

For Unittests you should only mock the direct dependencies. In your case you create PublicApi and inject a mock for ApiService and verify if PublicApi is calling the appropriate methods with the correct values on the ApiService Mock.

The same way you test all the other components isolated from the deeper dependencies.

If you want to test the combination of several components, that isn’t unit testing but rather integration testing. Therefore it depends of how you are putting your classes together. e.g. if you are using an IoC container, it probably supports replacing the configuration for the repositories in some way. In this case you can use the configuration of the application and replace the repositories and potentially also the views with mocks.