Hi, On Sun, Mar 22, 2015 at 1:35 AM, Johannes Schindelin <johannes.schindelin@xxxxxx> wrote: >> Maybe code coverage tools could help here so we only need to focus on >> the code paths that are untested by the test suite. At the minimum, >> all of the non-trivial code paths in both the shell script and the >> converted builtin must be covered by tests. This should help to >> eliminate most sources of breakages. Anything further than that would >> require an experienced understanding of all the possible important >> inputs to be tested, which I personally feel would make the project >> quite tedious. >> >> I see git already has gcov support. For shell scripts, maybe kcov[1] >> could be used. With some slight code changes, I managed to generate a >> report for the git-pull tests[2] which should at least provide a good >> starting point for how the tests can be improved. > > While it is often a tempting idea to make test suites as thorough as possible, there lies a true danger herein. True war story: in one of the projects I was involved in, the test suite grew to a size that one complete run lasted two weeks. Yes, that is fourteen days. Needless to say: this test suite was run rarely. How useful is a test suite that is run rarely? More useful than a non-existent one, to be sure, but it is still more of a burden than a boon. > > Now, on Windows the test suite takes almost three hours to run. This really, really slows down development. > > So while we are not yet at the "too large to be useful state", I would caution against trying to get there. > > Instead, I would really like to focus on the *usage*. Calling `git grep "git pull" t/` should give you an idea what usage of `git pull` is already tested. It should be pretty easy to come up with a list of *common* use cases, and if any of them are not covered, adding tests for them is simple and straight-forward, too. The code coverage tools can help here as well. The kcov output clearly shows which options of git-pull are currently not being tested. But yes, I agree that the test suite shouldn't be relied too much on compared to code inspection and review. On another important topic, though, along with git-pull.sh, I'm looking for another script to convert in parallel with git-pull.sh so that there will be no blocks due to patch review. Generally, I think rewriting scripts that are called frequently by users, or spawn a lot of processes due to loops, would be most desirable because the runtime gains would be much higher. A quick review of the scripts shows that git-am.sh, git-rebase--interactive.sh and git-quiltimport.sh have pretty heavy loops with lots of process spawning that grows with input. I'm currently leaning with git-am because not only is it a frequently used command, git-rebase--am.sh (for non-interactive rebase) calls it as well. In fact, quick tests show that it takes up 98% of git-rebase's execution time on Windows, so if git-am's performance improves it would be a huge win on many fronts. git-am's code also seems to be manageable for a 3-month project. Anyway, I would like to know if you (or anyone else) have any scripts in mind. (I also think that just 2 scripts would be enough to fill the 3 months, but that might be me just being too conservative) Regards, Paul -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html