Handle SIGWINCH under bazel run //some:test (i.e. test rules) cor…

…rectly. (#17760)

Previously, after two window resize events we would stop waiting for the child process.

`wait` is interrupted by any trapped signal (and we trap all signals), so we need to call it in a loop until the child really exited.

Fixes #17215

Closes #17301.

PiperOrigin-RevId: 514395755
Change-Id: Ifb763a55d53f230cde8b1ca77761d94ea6e43e1f

Co-authored-by: Tobias Werth <twerth@google.com>

tools/test/test-setup.sh

@@ -352,13 +352,15 @@ cleanupPid=$!
 
 set +m
 
+# Wait until $childPid fully exits.
+# We need to wait in a loop because wait is interrupted by any incoming trapped
+# signal (https://www.gnu.org/software/bash/manual/bash.html#Signals).
+while kill -0 $childPid 2>/dev/null; do
+  wait $childPid
+done
+# Wait one more time to retrieve the exit code.
 wait $childPid
-# If interrupted by a signal, use the signal as the exit code. But allow
-# the child to actually finish from the signal we sent _it_ via signal_child.
-# (Waiting on a stopped process is a no-op).
-# Only once - if we receive multiple signals (of any sort), give up.
 exitCode=$?
-wait $childPid
 
 # By this point, we have everything we're willing to wait for. Tidy up our own
 # processes and move on.