Move cgroups package into libcontainer

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

libcontainer/cgroups/fs/test_util.go

@@ -0,0 +1,75 @@
+/*
+Utility for testing cgroup operations.
+
+Creates a mock of the cgroup filesystem for the duration of the test.
+*/
+package fs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"testing"
+)
+
+type cgroupTestUtil struct {
+	// data to use in tests.
+	CgroupData *data
+
+	// Path to the mock cgroup directory.
+	CgroupPath string
+
+	// Temporary directory to store mock cgroup filesystem.
+	tempDir string
+	t       *testing.T
+}
+
+// Creates a new test util for the specified subsystem
+func NewCgroupTestUtil(subsystem string, t *testing.T) *cgroupTestUtil {
+	d := &data{}
+	tempDir, err := ioutil.TempDir("", fmt.Sprintf("%s_cgroup_test", subsystem))
+	if err != nil {
+		t.Fatal(err)
+	}
+	d.root = tempDir
+	testCgroupPath, err := d.path(subsystem)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Ensure the full mock cgroup path exists.
+	err = os.MkdirAll(testCgroupPath, 0755)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return &cgroupTestUtil{CgroupData: d, CgroupPath: testCgroupPath, tempDir: tempDir, t: t}
+}
+
+func (c *cgroupTestUtil) cleanup() {
+	os.RemoveAll(c.tempDir)
+}
+
+// Write the specified contents on the mock of the specified cgroup files.
+func (c *cgroupTestUtil) writeFileContents(fileContents map[string]string) {
+	for file, contents := range fileContents {
+		err := writeFile(c.CgroupPath, file, contents)
+		if err != nil {
+			c.t.Fatal(err)
+		}
+	}
+}
+
+// Expect the specified stats.
+func expectStats(t *testing.T, expected, actual map[string]float64) {
+	for stat, expectedValue := range expected {
+		actualValue, ok := actual[stat]
+		if !ok {
+			log.Printf("Expected stat %s to exist: %s", stat, actual)
+			t.Fail()
+		} else if actualValue != expectedValue {
+			log.Printf("Expected stats %s to have value %f but had %f instead", stat, expectedValue, actualValue)
+			t.Fail()
+		}
+	}
+}