tests/int: run rootless_cgroup tests for v2+systemd

Before this commit, "require rootless_cgroup" feature check required "cgroup"
to be present in ROOTLESS_FEATURES. The idea of the requirement, though, is
to ensure that rootless runc can manage cgroups.

In case of systemd + cgroup v2, rootless runc can manage cgroups,
thanks to systemd delegation, so modify the feature check accordingly.

Next, convert (simplify) some of the existing users to the modified check.

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

tests/integration/cgroups.bats

@@ -16,10 +16,7 @@ function setup() {
 }
 
 @test "runc create (rootless + no limits + cgrouppath + no permission) fails with permission error" {
-	requires rootless
-	requires rootless_no_cgroup
-	# systemd controls the permission, so error does not happen
-	requires no_systemd
+	requires rootless rootless_no_cgroup
 
 	set_cgroups_path
 
@@ -29,10 +26,7 @@ function setup() {
 }
 
 @test "runc create (rootless + limits + no cgrouppath + no permission) fails with informative error" {
-	requires rootless
-	requires rootless_no_cgroup
-	# systemd controls the permission, so error does not happen
-	requires no_systemd
+	requires rootless rootless_no_cgroup
 
 	set_resources_limit
 

tests/integration/helpers.bash

@@ -271,6 +271,11 @@ function fail() {
 	exit 1
 }
 
+# Check whether rootless runc can use cgroups.
+function rootless_cgroup() {
+	[[ "$ROOTLESS_FEATURES" == *"cgroup"* || -n "$RUNC_USE_SYSTEMD" ]]
+}
+
 # Allows a test to specify what things it requires. If the environment can't
 # support it, the test is skipped with a message.
 function requires() {
@@ -298,12 +303,12 @@ function requires() {
 			fi
 			;;
 		rootless_cgroup)
-			if [[ "$ROOTLESS_FEATURES" != *"cgroup"* ]]; then
+			if ! rootless_cgroup; then
 				skip_me=1
 			fi
 			;;
 		rootless_no_cgroup)
-			if [[ "$ROOTLESS_FEATURES" == *"cgroup"* ]]; then
+			if rootless_cgroup; then
 				skip_me=1
 			fi
 			;;

tests/integration/update.bats

@@ -21,7 +21,7 @@ function setup() {
 # Tests whatever limits are (more or less) common between cgroup
 # v1 and v2: memory/swap, pids, and cpuset.
 @test "update cgroup v1/v2 common limits" {
-	[[ "$ROOTLESS" -ne 0 && -z "$RUNC_USE_SYSTEMD" ]] && requires rootless_cgroup
+	[[ "$ROOTLESS" -ne 0 ]] && requires rootless_cgroup
 	requires cgroups_memory cgroups_pids cgroups_cpuset
 	init_cgroup_paths