runtime: Move mockfs control global into mockfs.go

virtcontainers/persist/fs/mockfs.go defines a mock filesystem type for
testing.  A global variable in virtcontainers/persist/manager.go is used to
force use of the mock fs rather than a normal one.

This patch moves the global, and the EnableMockTesting() function which
sets it into mockfs.go.  This is slightly cleaner to begin with, and will
allow some further enhancements.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

src/runtime/virtcontainers/persist/fs/mockfs.go

@@ -13,11 +13,17 @@ import (
 	persistapi "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/persist/api"
 )
 
+var mockTesting = false
+
 type MockFS struct {
 	// inherit from FS. Overwrite if needed.
 	*FS
 }
 
+func EnableMockTesting() {
+	mockTesting = true
+}
+
 func MockStorageRootPath() string {
 	return filepath.Join(os.TempDir(), "vc", "mockfs")
 }
@@ -46,3 +52,10 @@ func MockFSInit() (persistapi.PersistDriver, error) {
 
 	return &MockFS{fsDriver}, nil
 }
+
+func MockAutoInit() (persistapi.PersistDriver, error) {
+	if mockTesting {
+		return MockFSInit()
+	}
+	return nil, nil
+}

src/runtime/virtcontainers/persist/fs/mockfs_test.go

@@ -0,0 +1,34 @@
+// Copyright Red Hat.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package fs
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMockAutoInit(t *testing.T) {
+	assert := assert.New(t)
+	orgMockTesting := mockTesting
+	defer func() {
+		mockTesting = orgMockTesting
+	}()
+
+	mockTesting = false
+
+	fsd, err := MockAutoInit()
+	assert.Nil(fsd)
+	assert.NoError(err)
+
+	// Testing mock driver
+	mockTesting = true
+	fsd, err = MockAutoInit()
+	assert.NoError(err)
+	expectedFS, err := MockFSInit()
+	assert.NoError(err)
+	assert.Equal(expectedFS, fsd)
+}

src/runtime/virtcontainers/persist/manager.go

@@ -28,13 +28,8 @@ var (
 		RootFSName:     fs.Init,
 		RootlessFSName: fs.RootlessInit,
 	}
-	mockTesting = false
 )
 
-func EnableMockTesting() {
-	mockTesting = true
-}
-
 // GetDriver returns new PersistDriver according to driver name
 func GetDriverByName(name string) (persistapi.PersistDriver, error) {
 	if expErr != nil {
@@ -56,8 +51,9 @@ func GetDriver() (persistapi.PersistDriver, error) {
 		return nil, expErr
 	}
 
-	if mockTesting {
-		return fs.MockFSInit()
+	mock, err := fs.MockAutoInit()
+	if mock != nil || err != nil {
+		return mock, err
 	}
 
 	if rootless.IsRootless() {

src/runtime/virtcontainers/persist/manager_test.go

@@ -27,12 +27,6 @@ func TestGetDriverByName(t *testing.T) {
 
 func TestGetDriver(t *testing.T) {
 	assert := assert.New(t)
-	orgMockTesting := mockTesting
-	defer func() {
-		mockTesting = orgMockTesting
-	}()
-
-	mockTesting = false
 
 	fsd, err := GetDriver()
 	assert.NoError(err)
@@ -46,12 +40,4 @@ func TestGetDriver(t *testing.T) {
 
 	assert.NoError(err)
 	assert.Equal(expectedFS, fsd)
-
-	// Testing mock driver
-	mockTesting = true
-	fsd, err = GetDriver()
-	assert.NoError(err)
-	expectedFS, err = fs.MockFSInit()
-	assert.NoError(err)
-	assert.Equal(expectedFS, fsd)
 }

src/runtime/virtcontainers/virtcontainers_test.go

@@ -15,7 +15,6 @@ import (
 	"syscall"
 	"testing"
 
-	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/persist"
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/persist/fs"
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/utils"
 	"github.com/sirupsen/logrus"
@@ -108,7 +107,7 @@ func setupClh() {
 func TestMain(m *testing.M) {
 	var err error
 
-	persist.EnableMockTesting()
+	fs.EnableMockTesting()
 
 	flag.Parse()