Unit testing with generated DAL code

Question

I use a code generator (CodeSmith with .NetTiers template) to generate all the DAL code. I write unit tests for my code (business layer), and these tests are becoming pretty slow to run. The problem is that for each test, I reset the database to have a clean state. Also, as I do a lot of tests, it seems that the latency of the database operations sum up to a pretty bit delay.

All DB operations are performed through a DataRepository class that is generated by .NetTiers. Do you know if there is a way to generate (or code myself) a mock-DataRepository that would use in-memory storage instead of using the database ?

This way, I would be able to use this mock repository in my unit tests, speeding them a lot, without actually changing anything to my current code !

Answer 1

Some of our unit tests use data fetched from XML's which were generated from a database to mock db access. DAL classes are replaced by mock ones because they are all stored in a DI container.

The generation of the xml's is custom code, if you find an open source solution for this then I'm happy to hear it.

Edit after Stefan's answer: I recall another team using SQL CE for their test database

Answer 2

Take a look at Dependency injection (DI) and Inversion of Control containers (IOC). Essentially, you will create an interface that that a new mock DB object can implement, and then the DI framework will inject your mock DB when running tests, and the real DB when running you app.

There are numerous free and open source libraries that you could use to help you out. Since you are in C#, one of the new and up and coming DI libraries is Ninject. There are many others too. Check out this Wikipedia article for others and a high level description.

Answer 3

From the description of the issue, I think you are performing the Integration test because your test is making use of the Business and the DAL and live database.

For unit testing, you deal with one layer of code with all other dependencies either mocked or stubbed. With this approach, you unit tests will be really fast to execute on every incremental code changes.

There are various mocking frameworks that you can use like Rhino Mock, Moq, typemock to name a few. (In my project, I use Rhino mock to mock the DAL layer and unit test Business Layer in Isolation)

Harsha