Question

I just wondered what the differences with unit testing and implementation testing are. I know unit testing is testing your modules/class/objects using defined inputs and checking the results against some defined outputs but what does implementation testing do and how do you do it? Also where does implementation testing fit in the development lifecycle?

Answer 1

“implementation testing” is not a common expression. I suspect that you meant “integration testing”, since that is commonly used, especially in contrast to unit testing.

Integration testing means testing multiple parts or all of the system acting together. Often, the tests simulate an actual user working with the system through its regular UI.

The advantage is that you don’t just test whether each component fulfils its contract, but also whether they are composed and configured correctly and interact as expected – things that you can’t catch with unit tests. On the other hand, it’s often hard to exhaustively test boundary conditions with integration tests, they’re less stable and take much longer to execute. And of course they cannot be run (or even written) until most of the system is working.

Thus, integration tests happen much later in the development lifecycle than unit tests.