cgroups: don't use d.path for cgroup tests files

d.path() should be used to get the real cgroup path, for temp path,
we can just create one.

Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>

cgroups/fs/devices_test.go

@@ -25,7 +25,7 @@ func TestDevicesSetAllow(t *testing.T) {
 	defer helper.cleanup()
 
 	helper.writeFileContents(map[string]string{
-		"device.deny": "a",
+		"devices.deny": "a",
 	})
 
 	helper.CgroupData.c.AllowAllDevices = false
@@ -35,8 +35,6 @@ func TestDevicesSetAllow(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	// FIXME: this doesn't make sence, the file devices.allow under real cgroupfs
-	// is not allowed to read. Our test path don't have cgroupfs mounted.
 	value, err := getCgroupParamString(helper.CgroupPath, "devices.allow")
 	if err != nil {
 		t.Fatalf("Failed to parse devices.allow - %s", err)

cgroups/fs/util_test.go

@@ -6,9 +6,9 @@ Creates a mock of the cgroup filesystem for the duration of the test.
 package fs
 
 import (
-	"fmt"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/docker/libcontainer/configs"
@@ -31,12 +31,12 @@ func NewCgroupTestUtil(subsystem string, t *testing.T) *cgroupTestUtil {
 	d := &data{
 		c: &configs.Cgroup{},
 	}
-	tempDir, err := ioutil.TempDir("", fmt.Sprintf("%s_cgroup_test", subsystem))
+	tempDir, err := ioutil.TempDir("", "cgroup_test")
 	if err != nil {
 		t.Fatal(err)
 	}
 	d.root = tempDir
-	testCgroupPath, err := d.path(subsystem)
+	testCgroupPath := filepath.Join(d.root, subsystem)
 	if err != nil {
 		t.Fatal(err)
 	}