tests/rootless.sh: use set -e -u -o pipefail

Currently, set -e ("exit on error") is only set before running tests.
The bad consequence is the script may fail to set up test environment
but will still run the tests.

Use "set -e -u -o pipefail" for the whole script to catch potential
issues with test setup and/or the script itself.

Note we have to set RUNC_USE_SYSTEMD to an empty value if it is unset,
so that the subsequent checks like [ -z "$RUNC_USE_SYSTEMD" ] won't
trigger a "unbound variable" errors.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

tests/rootless.sh

@@ -19,6 +19,9 @@
 # a new feature, please match the existing style. Add an entry to $ALL_FEATURES,
 # and add an enable_* and disable_* hook.
 
+set -e -u -o pipefail
+[ -v RUNC_USE_SYSTEMD ] || RUNC_USE_SYSTEMD=
+
 ALL_FEATURES=("idmap" "cgroup")
 # cgroup is managed by systemd when RUNC_USE_SYSTEMD is set
 if [[ -n "${RUNC_USE_SYSTEMD}" ]]; then
@@ -150,6 +153,7 @@ features_powerset="$(powerset "${ALL_FEATURES[@]}")"
 
 # Iterate over the powerset of all features.
 IFS=:
+idx=0
 for enabled_features in $features_powerset; do
 	idx="$(($idx + 1))"
 	echo "[$(printf '%.2d' "$idx")] run rootless tests ... (${enabled_features%%+})"
@@ -162,7 +166,6 @@ for enabled_features in $features_powerset; do
 	done
 
 	# Run the test suite!
-	set -e
 	echo path: $PATH
 	export ROOTLESS_FEATURES="$enabled_features"
 	if [[ -n "${RUNC_USE_SYSTEMD}" ]]; then
@@ -173,6 +176,5 @@ for enabled_features in $features_powerset; do
 	else
 		sudo -HE -u rootless PATH="$PATH" $(which bats) -t "$ROOT/tests/integration$ROOTLESS_TESTPATH"
 	fi
-	set +e
 	cleanup
 done