This patch added a whole lot of test cases, and two of them '86 -
proc-receive: not support push options (builtin protocol)' and '95 -
proc-receive: not support push options (builtin protocol/porcelain)'
are prone to rare failures.
On Thu, Aug 27, 2020 at 11:45:44AM -0400, Jiang Xin wrote:
> diff --git a/t/t5411/test-0026-push-options.sh b/t/t5411/test-0026-push-options.sh
> new file mode 100644
> index 0000000000..d0c4da8b23
> --- /dev/null
> +++ b/t/t5411/test-0026-push-options.sh
> +# Refs of upstream : master(A)
> +# Refs of workbench: master(A) tags/v123
> +# git push -o ... : refs/for/master/topic
> +test_expect_success "proc-receive: not support push options ($PROTOCOL)" '
> + test_must_fail git -C workbench push \
> + -o issue=123 \
> + -o reviewer=user1 \
> + origin \
> + HEAD:refs/for/master/topic \
> + >out 2>&1 &&
Three relevant things are happening here:
- 'git push' is executed with its standard output and error
redirected to the file 'out'.
- 'git push' executes 'git receive-pack' internally, which inherits
the open file descriptors, so its output and error goes into that
same 'out' file.
- 'git push' is expected to fail when it finds out that the other
side doesn't support push options, but it does so with a simple
die() right away, without waiting for its child 'git receive-pack'
process to finish.
> + make_user_friendly_and_stable_output <out >actual &&
> + test_i18ngrep "fatal: the receiving end does not support push options" \
> + actual &&
> + git -C "$upstream" show-ref >out &&
Here the shell opens and truncates the file 'out' to write 'git
show-ref's output, i.e. it is still the same 'out' file that was used
earlier.
Consequently, it is possible that 'git receive-pack' is still running,
its open file descriptors to 'out' are still valid, and its "fatal:
the remote end hung up unexpectedly" error message about the suddenly
disappeared 'git push' can partially overwrite the output from 'git
show-ref'.
> + make_user_friendly_and_stable_output <out >actual &&
> + cat >expect <<-EOF &&
> + <COMMIT-A> refs/heads/master
> + EOF
> + test_cmp expect actual
> +'
The supposedly stable output can then unexpectedly include that error
message, and the test fails with something like this:
+ test_cmp expect actual
--- expect 2021-01-17 21:55:23.430750004 +0000
+++ actual 2021-01-17 21:55:23.430750004 +0000
@@ -1 +1 @@
-<COMMIT-A> refs/heads/main
+<COMMIT-A> refs/heads/maifatal: the remote end hung up unexpectedly
error: last command exited with $?=1
not ok 86 - proc-receive: not support push options (builtin protocol)
> diff --git a/t/t5411/test-0027-push-options--porcelain.sh b/t/t5411/test-0027-push-options--porcelain.sh
> new file mode 100644
> index 0000000000..c89a1e7c57
> --- /dev/null
> +++ b/t/t5411/test-0027-push-options--porcelain.sh
> +test_expect_success "proc-receive: not support push options ($PROTOCOL/porcelain)" '
> + test_must_fail git -C workbench push \
> + --porcelain \
> + -o issue=123 \
> + -o reviewer=user1 \
> + origin \
> + HEAD:refs/for/master/topic \
> + >out 2>&1 &&
> + make_user_friendly_and_stable_output <out >actual &&
> + test_i18ngrep "fatal: the receiving end does not support push options" \
> + actual &&
> + git -C "$upstream" show-ref >out &&
> + make_user_friendly_and_stable_output <out >actual &&
> + cat >expect <<-EOF &&
> + <COMMIT-A> refs/heads/master
> + EOF
> + test_cmp expect actual
> +'
This test is almost identical to the one above, and the same sequence
of events leads to a similar failure.
I saw these tests fail in Travis CI's s390x environment a couple of
times, and, alas, that is the only environment where I was able to
reproduce the failure with '--stress' with an unmodified Git.
The diff below adds a couple of strategically-placed delays to
reliably demonstrate these failures:
--- >8 ---
diff --git a/pkt-line.c b/pkt-line.c
index d633005ef7..3b26631948 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -307,6 +307,7 @@ static int get_packet_data(int fd, char **src_buf, size_t *src_size,
if (options & PACKET_READ_GENTLE_ON_EOF)
return -1;
+ sleep(1);
die(_("the remote end hung up unexpectedly"));
}
diff --git a/t/t5411/test-0026-push-options.sh b/t/t5411/test-0026-push-options.sh
index e88edb16a4..a1e896f404 100644
--- a/t/t5411/test-0026-push-options.sh
+++ b/t/t5411/test-0026-push-options.sh
@@ -21,6 +21,7 @@ test_expect_success "proc-receive: not support push options ($PROTOCOL)" '
test_i18ngrep "fatal: the receiving end does not support push options" \
actual &&
git -C "$upstream" show-ref >out &&
+ sleep 2 &&
make_user_friendly_and_stable_output <out >actual &&
cat >expect <<-EOF &&
<COMMIT-A> refs/heads/main
diff --git a/t/t5411/test-0027-push-options--porcelain.sh b/t/t5411/test-0027-push-options--porcelain.sh
index 3a6561b5ea..f97cef440f 100644
--- a/t/t5411/test-0027-push-options--porcelain.sh
+++ b/t/t5411/test-0027-push-options--porcelain.sh
@@ -22,6 +22,7 @@ test_expect_success "proc-receive: not support push options ($PROTOCOL/porcelain
test_i18ngrep "fatal: the receiving end does not support push options" \
actual &&
git -C "$upstream" show-ref >out &&
+ sleep 2 &&
make_user_friendly_and_stable_output <out >actual &&
cat >expect <<-EOF &&
<COMMIT-A> refs/heads/main
--- 8< ---
I think these are the only two tests that can cause this racy
behavior: by instrumenting finish_command() I found that in all other
tests where 'git push' is expected to fail it errors out gracefully
and waits for its 'git receive-pack' child process.
