How do I integration testing to my code written using the ASP.NET Provider Model?

Question

I'm fairly new to unit testing. I have a site built in the 3-tier architecture, UI -> BLL -> DAL. And I used the asp.net Provider Model, so by making changes to web.config I can switch to DAL dll to target different data sources, to be complete the DAL is written with Entity Framework.

Now, my question is how do I unit test my BLL? I use NUnit.

If run/debug my site, the asp.net/IIS loads everything and gets the correct configuration from web.config, so things work, that is because the entry point is from IIS. Now if I use NUnit gui to test and say I have my test project "MySite.Test.dll" which have test cases to my BLL, how does the testing framework get the correct configuration to successfully run all the test. It needs the info in web.config to load the correct provider!

Now, in my DAL there is a App.config created there by EntityFramework, and in it there is just the connectionString. Should I put all the provider related configuration in this app.config? Or am I missing some big picture on how to correctly do this?

This should be a common thing I imagine people need to do constantly. Could someone give some detail on how do I unit test my lib.

Thank you, Ray.

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Edit: After reading the first 2 answers I think I should correct my description with integration testing. Basically instead of IIS as the entry point, use GUI tools like the NUnit to run and test my code through, so NUnit -> BLL -> DAL. How do people actually set it up?

Thanks, Ray.

Answer 1

Looks like what you are trying to do - is integration testing... Unit testing, by definition, testing Plain Old .Net Classes in isolation. No database, no configuration...so...as I see it, to do proper unit testing, you need to refactor your BLL to service layer and domain logic classes which you will test separately. Like: Service layer uses domain logic classes, and your unit test uses them. So, domain classes do not go to database, and you do not need connection strings and everything.

However, if you want to do proper integration testing with database, you might want to do that too. If this is what you need - google it, it's not difficult to get some configuration strings in nunit.config or something...I don't know the details.

However, I feel what you want to do is unit testing and not integration testing..

Ask yourself, WHAT EXACTLY DO I WANT TO TEST? Unit testing does not test "everything". Refactor, invert dependencies, and try to test you business logic in isolation.

Answer 2

You have a couple of different options depending on how isolated you want to be from the DAL. If you want to involve the DAL in your tests, then you can copy the connection string section of the app.config file to an app.config file in your unit test project. As @badbadboy says, though, this really is integration testing, not unit testing.

If you want to do proper unit testing you probably want to use dependency injection and interfaces to allow you to mock out the DAL from your BLL. I use LINQ-to-SQL so what I do is create an interface and wrapper class around the DataContext. This allows me to create a mock database to use for unit testing to test my entity classes in isolation.

Testing your entity classes in isolation will make your tests less brittle and allow you to set up the data for each test independently. This makes it much easier to maintain.

You also might want to look into a mocking framework that will make it almost trivial to generate the mock objects. I've had pretty good success with Rhino Mocks, but there are others.

Answer 3

Instead of a "web.config" file in your unit test project, you'll need a "MySite.Test.dll.config" file instead where you can enter the correct configuration for the testing. Note, using this method you could use a different provider to connect to an in-memory database instead if you wanted.