On Fri, Nov 18 2022, Taylor Blau wrote: > On Fri, Nov 18, 2022 at 03:19:55PM -0800, Junio C Hamano wrote: >> Well "! test_cmp" is wrong anyway, because it _expects_ two files >> are the same and gives more detailed diagnosis when they differ by >> giving "diff" output. >> >> If you expect them to be different, "! test_cmp" would give >> "detailed diagnosis" in the wrong case, i.e. the outcome is what we >> expect. > > I agree that "! test_cmp foo bar" will give output about how "foo" is > different from "bar" (and halt the test only when the two have the same > contents). > >> So the caller must do "test_cmp !" whether the underlying >> implementation of test_cmp uses "diff -u" or "diff --no-index". > > But this confuses me. "git grep 'test_cmp !'" turns up no results, and > furthermore, test_cmp() itself begins with: > > test "$#" -ne 2 && BUG "2 param" > > So I am not sure what you are referring to. I think we've got got a bit sidetracked here. Junio's pointing out that a test that would do: ! diff a b Is pretty stupid, why would you want to show a diff of differences, if you're expecting it to be different? Just use: ! cmp a b Or something. That's correct. So I think probably those "! test_cmp" uses would be good candidates for some clean-up to make the test suite pretty. But what I'm pointing out is that by having "test_cmp" be something that invokes "git" (or a helper) we *must not* negate it using the shell's negation, we have to use "test_must_fail" for anything we build ourselves. So, the proposed patch would make the existing cases where we do: ! test_cmp Cases where we'd hide a segfault, whereas before it was maybe a bit odd, but harmless, and working as intended in the sense of reliably passing if we had differences. So no, nothing currently does "test_cmp !", I was suggesting that upthread as the least invasive way of having "test_cmp" safe'd under negation, now that we were having it call out to "git diff" (or a helper...). It's the pattern we use for our own test helpers that invoke our own binaries (and if we don't, that's a bug).
