Question

I have been doing a lot of unit testing lately with mocking. The one thing that strikes me as a bit of a problem are the differences between querying against an in memory list (via a mock of my repository) and querying directly against the database via entity framework.

Some of these situations might be:

1. Testing a filter parameter which would be case insensitive against a database but case sensitive
   against an in memory collection leading to a false fail.

2. Linq statements that might pass against an in memory collection but would fail against entity framework because they arent supported leading to a false pass.

What is the correct way to handle or account for these differences so that there are not false passes or fails in tests? I really like mocking as it makes things so much quicker and easier to test. But it seems to me that the only way to get a really accurate test would be to just test against a the entity framework/database environment.

Answer 1

Besides the unit tests you do you should also create integration tests which run against a real database setup as encountered in production.

I’m not an expert for EF but with NHibernate for example you can create a configuration which points to an in-memory instance of SQLite where you then run your quick tests against (i.e. during a development cycle where you want to get through the test suite as fast as possible). When you want to run your integration tests against a real database you simply change the NHibernate config to point to a real database setup and run the same tests again.

Would be surprising if you could not achieve something similar with EF.