How to start unit testing or TDD?

Question

I read a lot of posts that convinced me I should start writing unit test, I also started to use dependency injection (Unity) for the sake of easier mocking, but I\'m still n

Answer 1

I have worked for companies which take unit testing/integration testing too far and those that do too little so I like to think I have a good balance between the two.

I would recommend TDD - Test Driven Development. This ensures you have good coverage but it also keeps focusing your attention on the right place and problem.

So the first thing you do for every piece of new development is write a unit test - even if you don't have a single class to test.

Think about what you are testing. Now run the test. Why wouldn't it compile? Because you need classA. Create the class and run the test. Why doesn't it compile? Because it doesn't have methodA. Write method one and run unit test again. Why does the test fail? Because methodA isn't implemented. Implement methodA and run test. Why does it fail? Because methodA doesn't return the correct expected value...etc

You continue like this writing unit tests as you develop and then eventually the test will pass and the piece of functionality will be complete.

Answer 2

Extending on Steve Freeman's answer: Dave Astel's book is called "Test-driven Development - A practical guide". If the kind of application you're writing is a GUI application then this should be helpful. I read Kent Becks' book but I couldn't figure out how to start a project with TDD. Astel's book test-drives a complete non-trivial GUI application from start to finish using stories. It helped me a lot to acutally start with TDD, it showed me where and how to start.