[PATCH 2/6] t/lib-git-daemon: record daemon log

From: Jeff King <peff@peff.net>
Date: Jan 25, 2018, 00:55 UTC
Message-ID: <20180125005511.GB26850@sigill.intra.peff.net>
In-Reply-To: <20180125005447.GA26661@sigill.intra.peff.net>

When we start git-daemon for our tests, we send its stderr log stream to a named pipe. We synchronously read the first line to make sure that the daemon started, and then dump the rest to descriptor 4. This is handy for debugging test output with "--verbose", but the tests themselves can't access the log data.

Let's dump the log into a file, as well, so that future tests can check the log. There are two subtleties worth calling out here:

  - we replace "cat" with a subshell loop around "read" to
    ensure that there's no buffering (so that tests can be
    sure that after a request has been served, the matching
    log entries will have made it to the file)

  - we open the logfile for append, rather than just output.
    That makes it OK for tests to truncate the logfile
    without restarting the daemon (the OS will atomically
    seek to the end of the file when outputting each line).
    That allows tests to look at the log without worrying
    about pollution from earlier tests.

Signed-off-by: Jeff King <peff@peff.net>
---
 t/lib-git-daemon.sh | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/t/lib-git-daemon.sh b/t/lib-git-daemon.sh
index 987d40680b..19f3ffdbb1 100644
--- a/t/lib-git-daemon.sh
+++ b/t/lib-git-daemon.sh
@@ -53,11 +53,19 @@ start_git_daemon() {
 		"$@" "$GIT_DAEMON_DOCUMENT_ROOT_PATH" \
 		>&3 2>git_daemon_output &
 	GIT_DAEMON_PID=$!
+	>daemon.log
 	{
 		read line <&7
+		echo "$line"
 		echo >&4 "$line"
-		cat <&7 >&4 &
-	} 7<git_daemon_output &&
+		(
+			while read line <&7
+			do
+				echo "$line"
+				echo >&4 "$line"
+			done
+		) &
+	} 7<git_daemon_output >>"$TRASH_DIRECTORY/daemon.log" &&
 
 	# Check expected output
 	if test x"$(expr "$line" : "\[[0-9]*\] \(.*\)")" != x"Ready to rumble"

-- 
2.16.1.273.gfdaa03aa74