From: Ævar Arnfjörð Bjarmason Date: Wed, 22 Mar 2017 23:43:20 GMT Subject: Re: [PATCH v2 10/16] tag: change misleading --list documentation Message-ID: In-Reply-To: <20170322223600.huyel6j5wl644ddf@sigill.intra.peff.net> On Wed, Mar 22, 2017 at 11:36 PM, Jeff King wrote: > On Wed, Mar 22, 2017 at 03:26:21PM -0700, Junio C Hamano wrote: > >> Ævar Arnfjörð Bjarmason writes: >> >> > of things you think we should be putting in the test suite. I.e. >> > should the tests be: >> > >> > a) Only be a collection of invocations of git we'd be comfortable >> > showing to someone as "this works, and this is how you should do it", >> > or things that explicitly fail marked with test_must_fail. >> > >> > b) or a) && also various surprising combinations of things we don't >> > necessarily want to encourage or even support in the future, but which >> > are in there so if we change them, we at least know our change changed >> > something that worked before. >> >> I am strongly inclined to (a). If we cannot decide when we designed >> the feature, and we anticipate that we may want to change it later, >> then documenting the choice in a test or two may be a way to remind >> the choice we happened to have made, but in general I do not think >> we want to promise (to ourselves) more than what we are willing to >> commit to. > > I've occasionally[1] added tests that are "what we happen to produce > now", but I almost always mark them with a comment either in the test > script or in the commit message. What I'm _most_ concerned about is a > developer later breaking the test, but being unsure if they were > breaking some real-world case (and not being able to find clues in the > history). > > A secondary concern would be people using the test snippets as guidance > on what is normal or encouraged. > > So I could live with these patches, but I'd prefer to see a comment > somewhere. And I think I'd have a slight inclination to just stick to > (a) in the first place, unless there is a really good reason to cover > the test (like that we do not care between behaviors X and Y, but we > need to check that it does one of them, and not Z). Right, or in this case something where we're testing for behavior we documented for a long time, but never really intended to support. Junio would you be fine with just this on top: diff --git a/t/README b/t/README index 4982d1c521..9e079a360a 100644 --- a/t/README +++ b/t/README @@ -379,2 +379,5 @@ Do: + - Include tests which assert that the desired & recommended behavior + of commands is preserved. + - Put all code inside test_expect_success and other assertions. @@ -424,2 +427,17 @@ Don't: + - Include tests which exhaustively test for various edge cases or + unintended emergent behavior which we're not interested in + supporting in the future. + + An exception to this is are cases where we don't care about + different behaviors X and Y, but we need to check that it does one + of them, and not Z. + + Another exception are cases where our documentation might + unintentionally stated or implied that something was supported or + recommended, but we'd like to discourage its use going forward. + + In both of the above cases please prominently comment the test + indicating that you're testing for one of these two cases. + - exit() within a