At Agile 2009, I attended an interesting workshop on the problems of end-to-end testing. Here is the idea that I presented at the workshop:

I believe you need to have some end-to-end testing, because it helps you get fast feedback about end-to-end-related bugs. But we don't need to have a lot of those tests because then most of them test the same end-to-end-related stuff. The problem is that it is so easy to write those tests, especially for legacy code, so people end up having a lot of them. So a solution might be to put a limit on the amount of time that end-to-end testing is allowed to take. And of course we can let the build server enforce that limit by failing the build when the limit is exceeded. When a developer exceeds the limit, some of the end-to-end-tests must then be converted into isolated unit tests. When we only have a few end-to-end tests, neither their slowness nor their brittleness is such a big problem.

By Lars Thorup