Re: [PATCH] Make some commit hashes in tests reproducible
On Tue, Jul 07, 2020 at 04:54:18PM -0400, Jeff King wrote:
> Note that the patch above does seem to cause two tests to fail. One of
> them I _suspect_ is a raciness problem (order of commits output changes,
> which implies the original was expecting the time to increment between
> two commits without running test_tick).
It turns out this does depend on the system clock, but isn't racy in the traditional sense. See the explanation below (which might be worth doing even if we don't switch to a deterministic time everywhere else).
-- >8 --
Subject: [PATCH] t6000: use test_tick consistently
The first two commits created in t6000 are done without test_tick, meaning they use the current system clock. After that, we create one with test_tick, which means it uses a deterministic time in the past.
The result of the "symleft flag bit is propagated down from tag" test relies on the output order of commits from git-log, which in turn depends on these timestamps. So this test is technically dependent on the system clock time, though in practice it would only matter if your system clock was set before test_tick's default time (which is in 2005).
However, let's use test_tick consistently for those early commits (and update the expected output to match). This makes the test deterministic, which is in turn easier to reason about and debug.
Note that there's also a fourth commit here, and it does not use test_tick. It does have a deterministic timestamp because of the prior use of test_tick in the script, but it will always be the same time as the third commit. Let's use test_tick here, too, for consistency. The matching timestamps between the third and fourth commit are not an important part of the test.
We could also use test_commit in all of these cases, as it runs test_tick under the hood. But it would be awkward to do so, as these tests diverge from the usual test_commit patterns (e.g., by creating multiple files in a single commit).
Signed-off-by: Jeff King <peff@peff.net>
---
t/t6000-rev-list-misc.sh | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
Show changes to t/t6000-rev-list-misc.sh +5 −2
diff --git a/t/t6000-rev-list-misc.sh b/t/t6000-rev-list-misc.sh
index 3dc1ad8f71..3bb0e4ff8f 100755
--- a/t/t6000-rev-list-misc.sh
+++ b/t/t6000-rev-list-misc.sh
@@ -8,6 +8,7 @@ test_expect_success setup '
echo content1 >wanted_file &&
echo content2 >unwanted_file &&
git add wanted_file unwanted_file &&
+ test_tick &&
git commit -m one
'
@@ -21,6 +22,7 @@ test_expect_success 'rev-list --objects with pathspecs and deeper paths' '
mkdir foo &&
>foo/file &&
git add foo/file &&
+ test_tick &&
git commit -m two &&
git rev-list --objects HEAD -- foo >output &&
@@ -69,6 +71,7 @@ test_expect_success '--no-object-names and --object-names are last-one-wins' '
'
test_expect_success 'rev-list A..B and rev-list ^A B are the same' '
+ test_tick &&
git commit --allow-empty -m another &&
git tag -a -m "annotated" v1.0 &&
git rev-list --objects ^v1.0^ v1.0 >expect &&
@@ -84,10 +87,10 @@ test_expect_success 'propagate uninteresting flag down correctly' '
test_expect_success 'symleft flag bit is propagated down from tag' '
git log --format="%m %s" --left-right v1.0...master >actual &&
cat >expect <<-\EOF &&
- > two
- > one
< another
< that
+ > two
+ > one
EOF
test_cmp expect actual
'
--
2.27.0.730.gcc195a083d
Han-Wen Nienhuys via GitGitGadget
