cvsps: use a different tiebreaker to avoid flaky test
After adding some sneaky debug printing[0], I determined that this
test flaked when a CVS commit containing two files starts too close to
the end of a second, thus putting file "a" in one second and "b/c" in
the following second. The secondary sort key meant that these changes
sorted in a different order when the timestamps were different than
they did when they matched. As far as I can tell, CVS walks through
the files in a stable order, so by sorting on the filenames in cvsps
we'll get stable output. It's fine for us to switch from sorting on
the branchpoint as a secondary key because this was already the point
when we didn't care, and we're just trying to break ties in a stable
way. It's unclear to be if having the branchpoint present matters
anymore, but it doesn't really hurt to leave it.
With this change in place, I was able to run test-convert-cvs over 650
times in a row without a failure. test-convert-cvcs-synthetic.t
appears to still be flaky, but I don't think it's *worse* than it was
before - just not better (I observed one flaky failure in 200 runs on
that test).
0: The helpful debug hack ended up being this, in case it's useful to
future flaky test assassins:
--- a/hgext/convert/cvsps.py
+++ b/hgext/convert/cvsps.py
@@ -854,6 +854,8 @@ def debugcvsps(ui, *args, **opts):
ui.write(('Branch: %s\n' % (cs.branch or 'HEAD')))
ui.write(('Tag%s: %s \n' % (['', 's'][len(cs.tags) > 1],
','.join(cs.tags) or '(none)')))
+ if cs.comment == 'ci1' and (cs.id == 6) == bool(cs.branchpoints):
+ ui.write('raw timestamp %r\n' % (cs.date,))
if cs.branchpoints:
ui.write(('Branchpoints: %s \n') %
', '.join(sorted(cs.branchpoints)))
$ cat > writepatterns.py <<EOF
> import sys
>
> path = sys.argv[1]
> patterns = sys.argv[2:]
>
> fp = file(path, 'wb')
> for pattern in patterns:
> count = int(pattern[0:-1])
> char = pattern[-1] + '\n'
> fp.write(char*count)
> fp.close()
> EOF
prepare repo
$ hg init a
$ cd a
These initial lines of Xs were not in the original file used to generate
the patch. So all the patch hunks need to be applied to a constant offset
within this file. If the offset isn't tracked then the hunks can be
applied to the wrong lines of this file.
$ python ../writepatterns.py a 34X 10A 1B 10A 1C 10A 1B 10A 1D 10A 1B 10A 1E 10A 1B 10A
$ hg commit -Am adda
adding a
This is a cleaner patch generated via diff
In this case it reproduces the problem when
the output of hg export does not
import patch
$ hg import -v -m 'b' -d '2 0' - <<EOF
> --- a/a 2009-12-08 19:26:17.000000000 -0800
> +++ b/a 2009-12-08 19:26:17.000000000 -0800
> @@ -9,7 +9,7 @@
> A
> A
> B
> -A
> +a
> A
> A
> A
> @@ -53,7 +53,7 @@
> A
> A
> B
> -A
> +a
> A
> A
> A
> @@ -75,7 +75,7 @@
> A
> A
> B
> -A
> +a
> A
> A
> A
> EOF
applying patch from stdin
patching file a
Hunk #1 succeeded at 43 (offset 34 lines).
Hunk #2 succeeded at 87 (offset 34 lines).
Hunk #3 succeeded at 109 (offset 34 lines).
committing files:
a
committing manifest
committing changelog
created 189885cecb41
compare imported changes against reference file
$ python ../writepatterns.py aref 34X 10A 1B 1a 9A 1C 10A 1B 10A 1D 10A 1B 1a 9A 1E 10A 1B 1a 9A
$ diff aref a
$ cd ..