Remove Unicode normalization in difftree

Fixes #1057

Signed-off-by: Vadim Markovtsev <vadim@sourced.tech>

Author: vmarkovtsev

utils/merkletrie/difftree_test.go

@@ -475,8 +475,29 @@ func (s *DiffTreeSuite) TestIssue275(c *C) {
 	})
 }
 
+func (s *DiffTreeSuite) TestIssue1057(c *C) {
+	p1 := "TestAppWithUnicodéPath"
+	p2 := "TestAppWithUnicodéPath"
+	c.Assert(p1 == p2, Equals, false)
+	do(c, []diffTreeTest{
+		{
+			fmt.Sprintf("(%s(x.go<1>))", p1),
+			fmt.Sprintf("(%s(x.go<1>) %s(x.go<1>))", p1, p2),
+			fmt.Sprintf("+%s/x.go", p2),
+		},
+	})
+	// swap p1 with p2
+	do(c, []diffTreeTest{
+		{
+			fmt.Sprintf("(%s(x.go<1>))", p2),
+			fmt.Sprintf("(%s(x.go<1>) %s(x.go<1>))", p1, p2),
+			fmt.Sprintf("+%s/x.go", p1),
+		},
+	})
+}
+
 func (s *DiffTreeSuite) TestCancel(c *C) {
-	t :=  diffTreeTest{"()", "(a<> b<1> c() d<> e<2> f())", "+a +b +d +e"}
+	t := diffTreeTest{"()", "(a<> b<1> c() d<> e<2> f())", "+a +b +d +e"}
 	comment := Commentf("\n%s", "test cancel:")
 
 	a, err := fsnoder.New(t.from)

utils/merkletrie/noder/path.go

@@ -3,8 +3,6 @@ package noder
 import (
 	"bytes"
 	"strings"
-
-	"golang.org/x/text/unicode/norm"
 )
 
 // Path values represent a noder and its ancestors.  The root goes first
@@ -80,11 +78,9 @@ func (p Path) Compare(other Path) int {
 		case i == len(p):
 			return -1
 		default:
-			form := norm.Form(norm.NFC)
-			this := form.String(p[i].Name())
-			that := form.String(other[i].Name())
-
-			cmp := strings.Compare(this, that)
+			// We do *not* normalize Unicode here. CGit doesn't.
+			// https://github.com/src-d/go-git/issues/1057
+			cmp := strings.Compare(p[i].Name(), other[i].Name())
 			if cmp != 0 {
 				return cmp
 			}

utils/merkletrie/noder/path_test.go

@@ -156,6 +156,10 @@ func (s *PathSuite) TestCompareMixedDepths(c *C) {
 func (s *PathSuite) TestCompareNormalization(c *C) {
 	p1 := Path([]Noder{&noderMock{name: norm.Form(norm.NFKC).String("페")}})
 	p2 := Path([]Noder{&noderMock{name: norm.Form(norm.NFKD).String("페")}})
-	c.Assert(p1.Compare(p2), Equals, 0)
-	c.Assert(p2.Compare(p1), Equals, 0)
+	c.Assert(p1.Compare(p2), Equals, 1)
+	c.Assert(p2.Compare(p1), Equals, -1)
+	p1 = Path([]Noder{&noderMock{name: "TestAppWithUnicodéPath"}})
+	p2 = Path([]Noder{&noderMock{name: "TestAppWithUnicodéPath"}})
+	c.Assert(p1.Compare(p2), Equals, -1)
+	c.Assert(p2.Compare(p1), Equals, 1)
 }

worktree_test.go

@@ -365,8 +365,14 @@ func (s *WorktreeSuite) TestFilenameNormalization(c *C) {
 
 	w, err := server.Worktree()
 	c.Assert(err, IsNil)
-	util.WriteFile(w.Filesystem, filename, []byte("foo"), 0755)
-	_, err = w.Add(filename)
+
+	writeFile := func(path string) {
+		err := util.WriteFile(w.Filesystem, path, []byte("foo"), 0755)
+		c.Assert(err, IsNil)
+	}
+
+	writeFile(filename)
+	origHash, err := w.Add(filename)
 	c.Assert(err, IsNil)
 	_, err = w.Commit("foo", &CommitOptions{Author: defaultSignature()})
 	c.Assert(err, IsNil)
@@ -387,11 +393,32 @@ func (s *WorktreeSuite) TestFilenameNormalization(c *C) {
 	c.Assert(err, IsNil)
 
 	modFilename := norm.Form(norm.NFKD).String(filename)
-	util.WriteFile(w.Filesystem, modFilename, []byte("foo"), 0755)
+	writeFile(modFilename)
+
+	_, err = w.Add(filename)
+	c.Assert(err, IsNil)
+	modHash, err := w.Add(modFilename)
+	c.Assert(err, IsNil)
+	// At this point we've got two files with the same content.
+	// Hence their hashes must be the same.
+	c.Assert(origHash == modHash, Equals, true)
 
+	status, err = w.Status()
+	c.Assert(err, IsNil)
+	// However, their names are different and the work tree is still dirty.
+	c.Assert(status.IsClean(), Equals, false)
+
+	// Revert back the deletion of the first file.
+	writeFile(filename)
 	_, err = w.Add(filename)
 	c.Assert(err, IsNil)
-	_, err = w.Add(modFilename)
+
+	status, err = w.Status()
+	c.Assert(err, IsNil)
+	// Still dirty - the second file is added.
+	c.Assert(status.IsClean(), Equals, false)
+
+	_, err = w.Remove(modFilename)
 	c.Assert(err, IsNil)
 
 	status, err = w.Status()