run-tests: collect aggregate code coverage
Before this patch, every Python process during a code coverage run was
writing coverage data to the same file. I'm not sure if the coverage
package even tries to obtain a lock on the file. But what I do know is
there was some last write wins leading to loss of code coverage data, at
least with -j > 1.
This patch changes the code coverage mechanism to be multiple process
safe. The mechanism for initializing code coverage via sitecustomize.py
has been tweaked so each Python process will produce a separate coverage
data file on disk. Unless two processes generate the same random value,
there are no race conditions writing to the same file. At the end of the
test run, we combine all written files into an aggregate report.
On my machine, running the full test suite produces a little over
20,000 coverage files consuming ~350 MB. As you can imagine, it takes
several seconds to load and merge these coverage files. But when it is
done, you have an accurate picture of the aggregate code coverage for the
entire test suite, which is ~60% line coverage.
test that we don't interrupt the merge session if
a file-level merge failed
$ hg init repo
$ cd repo
$ echo foo > foo
$ echo a > bar
$ hg ci -Am 'add foo'
adding bar
adding foo
$ hg mv foo baz
$ echo b >> bar
$ echo quux > quux1
$ hg ci -Am 'mv foo baz'
adding quux1
$ hg up -qC 0
$ echo >> foo
$ echo c >> bar
$ echo quux > quux2
$ hg ci -Am 'change foo'
adding quux2
created new head
test with the rename on the remote side
$ HGMERGE=false hg merge
merging bar
merging bar failed!
merging foo and baz to baz
1 files updated, 1 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ hg resolve -l
U bar
R baz
test with the rename on the local side
$ hg up -C 1
3 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ HGMERGE=false hg merge
merging bar
merging bar failed!
merging baz and foo to baz
1 files updated, 1 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
show unresolved
$ hg resolve -l
U bar
R baz
unmark baz
$ hg resolve -u baz
show
$ hg resolve -l
U bar
U baz
$ hg st
M bar
M baz
M quux2
? bar.orig
re-resolve baz
$ hg resolve baz
merging baz and foo to baz
after resolve
$ hg resolve -l
U bar
R baz
resolve all warning
$ hg resolve
abort: no files or directories specified
(use --all to remerge all files)
[255]
resolve all
$ hg resolve -a
merging bar
warning: conflicts during merge.
merging bar incomplete! (edit conflicts, then use 'hg resolve --mark')
[1]
after
$ hg resolve -l
U bar
R baz
$ cd ..