More tests, better errors.

api/filesys/fileinfo.go

@@ -27,7 +27,7 @@ func (fi fileInfo) Mode() os.FileMode { return 0777 }
 // ModTime returns a bogus time
 func (fi fileInfo) ModTime() time.Time { return time.Time{} }
 
-// IsADir returns if it is a directory
+// IsDir returns true if it is a directory
 func (fi fileInfo) IsDir() bool { return fi.dir }
 
 // Sys should return underlying data source, but it now returns nil

api/filesys/filesystem.go

@@ -11,7 +11,8 @@ import (
 const (
 	Separator = string(filepath.Separator)
 	doubleSep = Separator + Separator
-	DotDir    = "."
+	SelfDir   = "."
+	ParentDir = ".."
 )
 
 // FileSystem groups basic os filesystem methods.
@@ -41,7 +42,8 @@ type FileSystem interface {
 	Glob(pattern string) ([]string, error)
 	// ReadFile returns the contents of the file at the given path.
 	ReadFile(path string) ([]byte, error)
-	// WriteFile writes the data to a file at the given path.
+	// WriteFile writes the data to a file at the given path,
+	// overwriting anything that's already there.
 	WriteFile(path string, data []byte) error
 	// Walk walks the file system with the given WalkFunc.
 	Walk(path string, walkFn filepath.WalkFunc) error

api/filesys/fsinmemory.go

@@ -120,7 +120,7 @@ func (fs *fsInMemory) ReadFile(name string) ([]byte, error) {
 	if ff, found := fs.m[name]; found {
 		return ff.content, nil
 	}
-	return nil, fmt.Errorf("cannot read file %q", name)
+	return nil, fmt.Errorf("'%s' doesn't exist", name)
 }
 
 // WriteFile always succeeds and does nothing.

api/filesys/util.go

@@ -19,3 +19,12 @@ func StripTrailingSeps(s string) string {
 	}
 	return s[:k]
 }
+
+// StripLeadingSeps trims leading filepath separators from input.
+func StripLeadingSeps(s string) string {
+	k := 0
+	for k < len(s) && s[k] == filepath.Separator {
+		k++
+	}
+	return s[k:]
+}

api/filesys/util_test.go

@@ -84,9 +84,9 @@ func TestFilePathSplit(t *testing.T) {
 			file: "",
 		},
 		{
-			full: DotDir,
+			full: SelfDir,
 			dir:  "",
-			file: DotDir,
+			file: SelfDir,
 		},
 		{
 			full: "rabbit.jpg",
@@ -163,3 +163,43 @@ func TestStripTrailingSeps(t *testing.T) {
 		}
 	}
 }
+
+func TestStripLeadingSeps(t *testing.T) {
+	cases := []struct {
+		full string
+		rem  string
+	}{
+		{
+			full: "foo",
+			rem:  "foo",
+		},
+		{
+			full: "",
+			rem:  "",
+		},
+		{
+			full: "/foo",
+			rem:  "foo",
+		},
+		{
+			full: "///foo///bar///",
+			rem:  "foo///bar///",
+		},
+		{
+			full: "/////",
+			rem:  "",
+		},
+		{
+			full: "/",
+			rem:  "",
+		},
+	}
+	for _, p := range cases {
+		dir := StripLeadingSeps(p.full)
+		if dir != p.rem {
+			t.Fatalf(
+				"in '%s', got dir='%s' (expected '%s')",
+				p.full, dir, p.rem)
+		}
+	}
+}