Fix URI extension and name to be correct on Windows

Many thanks to @mbaklor for figuring this out.
Should unblock #5958 failing Windows tests.

Author: Jacalz

storage/repository/uri.go

@@ -3,7 +3,7 @@ package repository
 import (
 	"bufio"
 	"mime"
-	"path/filepath"
+	"path"
 	"strings"
 	"unicode/utf8"
 
@@ -40,11 +40,11 @@ type uri struct {
 }
 
 func (u *uri) Extension() string {
-	return filepath.Ext(u.path)
+	return path.Ext(u.path)
 }
 
 func (u *uri) Name() string {
-	return filepath.Base(u.path)
+	return path.Base(u.path)
 }
 
 func (u *uri) MimeType() string {

storage/repository/uri_test.go

@@ -1,6 +1,11 @@
 package repository
 
-import "testing"
+import (
+	"runtime"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
 
 var benchString string
 
@@ -16,3 +21,39 @@ func BenchmarkURIString(b *testing.B) {
 
 	benchString = str
 }
+
+func TestURIExtension(t *testing.T) {
+	uri := NewFileURI("file")
+	assert.Equal(t, "", uri.Extension())
+
+	uri = NewFileURI("../file")
+	assert.Equal(t, "", uri.Extension())
+
+	uri = NewFileURI("file.txt")
+	assert.Equal(t, ".txt", uri.Extension())
+
+	uri = NewFileURI("file.tar.gz")
+	assert.Equal(t, ".gz", uri.Extension())
+}
+
+func TestURIName(t *testing.T) {
+	uri := NewFileURI("file")
+	assert.Equal(t, "file", uri.Name())
+
+	uri = NewFileURI("file.txt")
+	assert.Equal(t, "file.txt", uri.Name())
+
+	uri = NewFileURI("/somewhere/file.txt")
+	assert.Equal(t, "file.txt", uri.Name())
+
+	if runtime.GOOS == "windows" {
+		uri = NewFileURI("C://somewhere/file.txt")
+		assert.Equal(t, "file.txt", uri.Name())
+
+		uri = NewFileURI("C://somewhere")
+		assert.Equal(t, "somewhere", uri.Name())
+
+		uri = NewFileURI("C://")
+		assert.Equal(t, "C:", uri.Name())
+	}
+}