From: Simon McVittie <smcv@collabora.com>
Date: Sun, 18 Apr 2021 12:16:45 +0100
Subject: libtest: On failure, make it clearer what has happened

If we fail as a result of `set -x`, It's often not completely obvious
which command failed or how. Use a trap on ERR to show the command that
failed, and its exit status.

Signed-off-by: Simon McVittie <smcv@collabora.com>
Forwarded: https://github.com/ostreedev/ostree/pull/2350
---
 tests/libtest.sh | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tests/libtest.sh b/tests/libtest.sh
index eda3b92..2e9a99d 100755
--- a/tests/libtest.sh
+++ b/tests/libtest.sh
@@ -46,6 +46,14 @@ run_exit_cmds() {
 }
 trap run_exit_cmds EXIT
 
+report_err () {
+  local exit_status="$?"
+  { { local BASH_XTRACEFD=3; } 2> /dev/null
+  echo "Unexpected nonzero exit status $exit_status while running: $BASH_COMMAND" >&2
+  } 3> /dev/null
+}
+trap report_err ERR
+
 save_core() {
   if [ -e core ]; then
     cp core "$test_srcdir/core"