[weavie]

A developer can test their own code, but they will only test it through the paths that they are aware of and thus coded for. An independent tester needs to be there to explore different avenues and try things that a developer wouldn't have thought of. Developers do think very differently to users.

[michaelcampbell]

Yes, but that doesn't mean testers shouldn't also be developers.

Automation tests are as much code as the code they're testing.