mount: adding missing Join method

Author: mcuadros

helper/mount/mount.go

@@ -141,6 +141,10 @@ func (h *Mount) Symlink(target, link string) error {
 	return fs.Symlink(target, fullpath)
 }
 
+func (h *Mount) Join(elem ...string) string {
+	return h.underlying.Join(elem...)
+}
+
 func (h *Mount) Readlink(link string) (string, error) {
 	fs, fullpath, err := h.getSymlinkAndPath(link)
 	if err != nil {

helper/mount/mount_test.go

@@ -215,6 +215,14 @@ func (s *MountSuite) TestReadDir(c *C) {
 	c.Assert(s.Source.ReadDirArgs, HasLen, 0)
 }
 
+func (s *MountSuite) TestJoin(c *C) {
+	s.Helper.Join("foo", "bar")
+
+	c.Assert(s.Underlying.JoinArgs, HasLen, 1)
+	c.Assert(s.Underlying.JoinArgs[0], DeepEquals, []string{"foo", "bar"})
+	c.Assert(s.Source.JoinArgs, HasLen, 0)
+}
+
 func (s *MountSuite) TestReadDirInMount(c *C) {
 	_, err := s.Helper.ReadDir("foo/bar/qux")
 	c.Assert(err, IsNil)

test/mock.go

@@ -16,6 +16,7 @@ type BasicMock struct {
 	StatArgs     []string
 	RenameArgs   [][2]string
 	RemoveArgs   []string
+	JoinArgs     [][]string
 }
 
 func (fs *BasicMock) Create(filename string) (billy.File, error) {
@@ -49,6 +50,7 @@ func (fs *BasicMock) Remove(filename string) error {
 }
 
 func (fs *BasicMock) Join(elem ...string) string {
+	fs.JoinArgs = append(fs.JoinArgs, elem)
 	return path.Join(elem...)
 }