The Agile Way: Integration Testing vs Functional Testing or both?

Question

I work in an office which has been doing Agile for a while now. We use Scrum for project management and mix in the engineering practices of XP. It works well and we are constantly learning lessons and refining our process.

I would like to tell you about our usual practices for testing and get feedback on how this could be improved:

TDD: First Line of Defense We are quite religious about unit testing and I would say our developers are also experienced enough to write comprehensive tests and always isolate the SUT with mocks.

Integration Tests For our use, integration tests are basically the same as the unit tests just without using the mocks. This tends to catch a few issues which slipped through the unit tests. These tests tend to be difficult to read as they usually involve a lot or work in the before_each and after_each sections of the spec framework as the system has to often reach a certain state in order for the tests to be meaningful.

Functional Testing We usually do this in a structured, but manual fashion. We have played with Selenium and Windmill, which are cool, but for us at least not quite there yet.

I would like to hear how anyone else is doing things. Do you think that if Integration Tests or Functional Testing are being done well enough the other can be disregarded?

Answer 1

Unit, integration and functional testing, though exercising the same code, are attacking it from different perspectives. It's those perspectives that make the difference, if you were to drop one type of testing then something could work its way in from that angle.

Also, unit testing isn't really about testing your code, especially if you are practising TDD. The process of TDD helps you design your code better, you just get the added bonus of a suite of tests at the end of it.

You haven't mentioned whether you have a continuous integration server running. I would strongly recommend setting one up (Hudson is easy to set up). Then you can have your integration and functional tests run against every check in of the code.