Unit Testing in web applications that use databases

Question

I am building a web application that uses the database for Users, Security/roles, and to store content.

It seems a little daunting to me to begin on the road of unit testing because I have to make sure my database has been initialized properly for my tests to run.

What are common practices to help in this regard?

i.e. while developing/testing, I might delete a user, but for my test to pass that user has to be in the database, along with his profile, security settings etc.

I know I can create a setup script, something to recreat the databas etc.

I don't want to end up spending my entire time maintaining my tests and ensuring my database is in sych

Or is that the cost of Unit Testing/TDD?

Answer 1

The solution is Mocking. Mocks "replace" the connection. The unit under test will "connect" to the Mock and executes its statement. The Mock returns normal resultsets o.s.e.

After the test, the mock can give you a list of all methods, that were called by the unit under test. Easymock.org

As the other said: DB connection aren't a unit test. So drop it and do it local with Mocking objects

Answer 2

It's not a unit test if you are testing more than one unit.

Usually you'll have one component (your page, or the business layer) talking to a data layer object that is responsible for actually connecting and querying the database. My recommendation is to develop a unit test for the first component, using dependency injection to pass in a mock version of the DataLayer (which acts on hardcoded data, or a List you pass in, etc). This way you are testing your higher level code in isolation from the other components.

Then you are free to develop other unit tests (and integration tests) for the data layer to ensure that it is handling it's job (writing to the database) correctly.