Add unit test.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/server/helpers_test.go

@@ -17,13 +17,106 @@ limitations under the License.
 package server
 
 import (
+	"fmt"
+	"io"
+	"os"
+	"syscall"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"golang.org/x/net/context"
 
 	"github.com/kubernetes-incubator/cri-containerd/pkg/metadata"
+	ostesting "github.com/kubernetes-incubator/cri-containerd/pkg/os/testing"
 )
 
+func TestPrepareStreamingPipes(t *testing.T) {
+	for desc, test := range map[string]struct {
+		stdin  string
+		stdout string
+		stderr string
+	}{
+		"empty stdin": {
+			stdout: "/test/stdout",
+			stderr: "/test/stderr",
+		},
+		"empty stdout/stderr": {
+			stdin: "/test/stdin",
+		},
+		"non-empty stdio": {
+			stdin:  "/test/stdin",
+			stdout: "/test/stdout",
+			stderr: "/test/stderr",
+		},
+		"empty stdio": {},
+	} {
+		t.Logf("TestCase %q", desc)
+		c := newTestCRIContainerdService()
+		fakeOS := c.os.(*ostesting.FakeOS)
+		fakeOS.OpenFifoFn = func(ctx context.Context, fn string, flag int, perm os.FileMode) (io.ReadWriteCloser, error) {
+			expectFlag := syscall.O_RDONLY | syscall.O_CREAT | syscall.O_NONBLOCK
+			if fn == test.stdin {
+				expectFlag = syscall.O_WRONLY | syscall.O_CREAT | syscall.O_NONBLOCK
+			}
+			assert.Equal(t, expectFlag, flag)
+			assert.Equal(t, os.FileMode(0700), perm)
+			return nopReadWriteCloser{}, nil
+		}
+		i, o, e, err := c.prepareStreamingPipes(context.Background(), test.stdin, test.stdout, test.stderr)
+		assert.NoError(t, err)
+		assert.Equal(t, test.stdin != "", i != nil)
+		assert.Equal(t, test.stdout != "", o != nil)
+		assert.Equal(t, test.stderr != "", e != nil)
+	}
+}
+
+type closeTestReadWriteCloser struct {
+	CloseFn func() error
+	nopReadWriteCloser
+}
+
+func (c closeTestReadWriteCloser) Close() error {
+	return c.CloseFn()
+}
+
+func TestPrepareStreamingPipesError(t *testing.T) {
+	stdin, stdout, stderr := "/test/stdin", "/test/stdout", "/test/stderr"
+	for desc, inject := range map[string]map[string]error{
+		"should cleanup on stdin error":  {stdin: fmt.Errorf("stdin error")},
+		"should cleanup on stdout error": {stdout: fmt.Errorf("stdout error")},
+		"should cleanup on stderr error": {stderr: fmt.Errorf("stderr error")},
+	} {
+		t.Logf("TestCase %q", desc)
+		c := newTestCRIContainerdService()
+		fakeOS := c.os.(*ostesting.FakeOS)
+		openFlags := map[string]bool{
+			stdin:  false,
+			stdout: false,
+			stderr: false,
+		}
+		fakeOS.OpenFifoFn = func(ctx context.Context, fn string, flag int, perm os.FileMode) (io.ReadWriteCloser, error) {
+			if inject[fn] != nil {
+				return nil, inject[fn]
+			}
+			openFlags[fn] = !openFlags[fn]
+			testCloser := closeTestReadWriteCloser{}
+			testCloser.CloseFn = func() error {
+				openFlags[fn] = !openFlags[fn]
+				return nil
+			}
+			return testCloser, nil
+		}
+		i, o, e, err := c.prepareStreamingPipes(context.Background(), stdin, stdout, stderr)
+		assert.Error(t, err)
+		assert.Nil(t, i)
+		assert.Nil(t, o)
+		assert.Nil(t, e)
+		assert.False(t, openFlags[stdin])
+		assert.False(t, openFlags[stdout])
+		assert.False(t, openFlags[stderr])
+	}
+}
+
 func TestGetSandbox(t *testing.T) {
 	c := newTestCRIContainerdService()
 	testID := "abcdefg"