test-lib: clear watchman watches at test completion

The fsmonitor feature allows an external tool such as watchman to
monitor the working directory. The direct test
t7619-status-fsmonitor.sh provides some coverage, but it would be
better to run the entire test suite with watchman enabled. This
would provide more confidence that the feature is working as
intended.

When running the test suite in parallel with 'prove -j <N>', many
repos are created and deleted in parallel. When GIT_TEST_FSMONITOR
points to t/t7519/fsmonitor-watchman, this can lead to watchman
tracking many different folders, overloading its watch queue.

As a test script completes, we can tell watchman to stop watching
the directories inside the TRASH_DIRECTORY.

This is particularly important on Windows where watchman keeps an
open handle on the directories it watches, preventing them from
being deleted. There is currently a bug in watchman [1] where this
handle still is not closed, but if that is updated then these tests
can be run on Windows as well.

[1] facebook/watchman#764

Signed-off-by: Derrick Stolee <[email protected]>

Author: derrickstolee

t/test-lib-functions.sh

@@ -1475,3 +1475,18 @@ test_set_port () {
 	port=$(($port + ${GIT_TEST_STRESS_JOB_NR:-0}))
 	eval $var=$port
 }
+
+test_clear_watchman () {
+	if test -n "$GIT_TEST_FSMONITOR"
+	then
+		watchman watch-list |
+			grep "$TRASH_DIRECTORY" |
+			sed "s/\",//g" |
+			sed "s/\"//g" >repo-list
+
+		while read repo
+		do
+			watchman watch-del "$repo"
+		done <repo-list
+	fi
+}

t/test-lib.sh

@@ -1081,6 +1081,10 @@ test_atexit_handler () {
 test_done () {
 	GIT_EXIT_OK=t
 
+	# If watchman is being used with GIT_TEST_FSMONITOR, then
+	# clear all watches on directories inside the TRASH_DIRECTORY.
+	test_clear_watchman
+
 	# Run the atexit commands _before_ the trash directory is
 	# removed, so the commands can access pidfiles and socket files.
 	test_atexit_handler