How to correctly do unit-tests in ASP.NET MVC multi-layer application?

Question

I've used unit-tests in small ASP.NET MVC projects with monolithic architecture. In this case I just had 2 projects like SampleApplicationName and SampleApplicationName.Tests .

Now I am working in a team of 3 developers on a big project with really nice n-layer architecture. We have 5 projects in solution :

1.Data (POCO), 2.DataAccess (EF), 3.Common (helpers here), 4.Business, 5. UI (ASP.NET MVC5).

Here araise a question. How should I manage tests? Should it be separate test-projects for each exist project like Business.Tests, DataAccess.Tests , or I need to test only the final result? I mean that each method runs full path from UI -> BLL -> DAL, so should I test each project separately or have only one test project?

Answer 1

Usually you'll end up with

• a separate unit test project for each project with logic inside (if you're just keeping POCOs in a project it might not deserve a dedicated UT project) that are testable (you might want to skip the DataAccess layer)
• a couple of integration testing projects (UI & DataAccess layers might be good candidates here, although you might structure your IT projects in a different manner, by scenario - or even all together in a place)

I mean that each method runs full path from UI -> BLL -> DAL, so should I test each project separately or have only one test project?

So in this case you might target a separate UT project for each of them (although, again, that might be tricky to do with EF), and a single IT project that actually goes through the whole workflow.

Answer 2

In my experience you should unit test (or integration for the data layer) each layer separately and thoroughly. That's first, but once you have that in place it's a good idea to have a few end to end test for your actual product's features.