osfs: fix js implementation based on menfs

osfs/os_js.go

@@ -1,3 +1,5 @@
+// +build js
+
 package osfs
 
 import (
@@ -9,15 +11,7 @@ import (
 // globalMemFs is the global memory fs
 var globalMemFs = memfs.New()
 
-const (
-	defaultDirectoryMode = 0755
-	defaultCreateMode    = 0666
-)
-
-// OS is a filesystem shim for js.
-type OS struct{}
-
 // New returns a new OS filesystem.
 func New(baseDir string) billy.Filesystem {
-	return chroot.New(globalMemFs, baseDir)
+	return chroot.New(globalMemFs, globalMemFs.Join("/", baseDir))
 }

osfs/os_js_test.go

@@ -0,0 +1,47 @@
+// +build js
+
+package osfs
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/go-git/go-billy/v5"
+	"github.com/go-git/go-billy/v5/test"
+
+	. "gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type OSSuite struct {
+	test.FilesystemSuite
+	path        string
+	tempCounter int
+}
+
+var _ = Suite(&OSSuite{})
+
+func (s *OSSuite) SetUpTest(c *C) {
+	s.tempCounter++
+	s.path = fmt.Sprintf("test_%d", s.tempCounter)
+	s.FilesystemSuite = test.NewFilesystemSuite(New(s.path))
+}
+
+func (s *OSSuite) TestOpenDoesNotCreateDir(c *C) {
+	_, err := s.FS.Open("dir/non-existent")
+	c.Assert(err, NotNil)
+
+	_, err = s.FS.Stat(filepath.Join(s.path, "dir"))
+	c.Assert(os.IsNotExist(err), Equals, true)
+}
+
+func (s *OSSuite) TestCapabilities(c *C) {
+	_, ok := s.FS.(billy.Capable)
+	c.Assert(ok, Equals, true)
+
+	caps := billy.Capabilities(s.FS)
+	c.Assert(caps, Equals, billy.DefaultCapabilities&^billy.LockCapability)
+}

osfs/os_plan9.go

@@ -1,3 +1,5 @@
+// +build plan9
+
 package osfs
 
 import (

osfs/os_test.go

@@ -1,3 +1,5 @@
+// +build !js
+
 package osfs
 
 import (