formats: Index read support (#91)

* utils: fs generic TestSuite

* fs: fs.TempFile

* utils: fs small changes requested

* utils: fs, test fs.Create overwriting files

* formats: index, basic v2 reader

* formats: index, tree extension support

* formats: index, stage decoding

* formats: index, extended flags, v3 support

* formats: index, v4 support

* formats: index, Resolve undo support

* formats: index, fix error when decoding invalidated entries

* formats: index, fix style issues

1 files changed, 196 insertions, 0 deletions

diff --git a/formats/index/decoder_test.go b/formats/index/decoder_test.go
new file mode 100644
index 0000000..cf4c872
--- /dev/null
+++ b/formats/index/decoder_test.go
@@ -0,0 +1,196 @@
+package index
+
+import (
+	"testing"
+
+	. "gopkg.in/check.v1"
+	"gopkg.in/src-d/go-git.v4/core"
+	"gopkg.in/src-d/go-git.v4/fixtures"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type IdxfileSuite struct {
+	fixtures.Suite
+}
+
+var _ = Suite(&IdxfileSuite{})
+
+func (s *IdxfileSuite) TestDecode(c *C) {
+	f, err := fixtures.Basic().One().DotGit().Open("index")
+	c.Assert(err, IsNil)
+
+	idx := &Index{}
+	d := NewDecoder(f)
+	err = d.Decode(idx)
+	c.Assert(err, IsNil)
+
+	c.Assert(idx.Version, Equals, uint32(2))
+	c.Assert(idx.EntryCount, Equals, uint32(9))
+}
+
+func (s *IdxfileSuite) TestDecodeEntries(c *C) {
+	f, err := fixtures.Basic().One().DotGit().Open("index")
+	c.Assert(err, IsNil)
+
+	idx := &Index{}
+	d := NewDecoder(f)
+	err = d.Decode(idx)
+	c.Assert(err, IsNil)
+
+	c.Assert(idx.Entries, HasLen, 9)
+
+	e := idx.Entries[0]
+	c.Assert(e.CreatedAt.Unix(), Equals, int64(1473350251))
+	c.Assert(e.CreatedAt.Nanosecond(), Equals, 12059307)
+	c.Assert(e.ModifiedAt.Unix(), Equals, int64(1473350251))
+	c.Assert(e.ModifiedAt.Nanosecond(), Equals, 12059307)
+	c.Assert(e.Dev, Equals, uint32(38))
+	c.Assert(e.Inode, Equals, uint32(1715795))
+	c.Assert(e.UID, Equals, uint32(1000))
+	c.Assert(e.GID, Equals, uint32(100))
+	c.Assert(e.Size, Equals, uint32(189))
+	c.Assert(e.Hash.String(), Equals, "32858aad3c383ed1ff0a0f9bdf231d54a00c9e88")
+	c.Assert(e.Name, Equals, ".gitignore")
+	c.Assert(e.Mode.String(), Equals, "-rw-r--r--")
+
+	e = idx.Entries[1]
+	c.Assert(e.Name, Equals, "CHANGELOG")
+}
+
+func (s *IdxfileSuite) TestDecodeCacheTree(c *C) {
+	f, err := fixtures.Basic().One().DotGit().Open("index")
+	c.Assert(err, IsNil)
+
+	idx := &Index{}
+	d := NewDecoder(f)
+	err = d.Decode(idx)
+	c.Assert(err, IsNil)
+
+	c.Assert(idx.Entries, HasLen, 9)
+	c.Assert(idx.Cache.Entries, HasLen, 5)
+
+	for i, expected := range expectedEntries {
+		c.Assert(idx.Cache.Entries[i].Path, Equals, expected.Path)
+		c.Assert(idx.Cache.Entries[i].Entries, Equals, expected.Entries)
+		c.Assert(idx.Cache.Entries[i].Trees, Equals, expected.Trees)
+		c.Assert(idx.Cache.Entries[i].Hash.String(), Equals, expected.Hash.String())
+	}
+
+}
+
+var expectedEntries = []TreeEntry{
+	{Path: "", Entries: 9, Trees: 4, Hash: core.NewHash("a8d315b2b1c615d43042c3a62402b8a54288cf5c")},
+	{Path: "go", Entries: 1, Trees: 0, Hash: core.NewHash("a39771a7651f97faf5c72e08224d857fc35133db")},
+	{Path: "php", Entries: 1, Trees: 0, Hash: core.NewHash("586af567d0bb5e771e49bdd9434f5e0fb76d25fa")},
+	{Path: "json", Entries: 2, Trees: 0, Hash: core.NewHash("5a877e6a906a2743ad6e45d99c1793642aaf8eda")},
+	{Path: "vendor", Entries: 1, Trees: 0, Hash: core.NewHash("cf4aa3b38974fb7d81f367c0830f7d78d65ab86b")},
+}
+
+func (s *IdxfileSuite) TestDecodeMergeConflict(c *C) {
+	f, err := fixtures.Basic().ByTag("merge-conflict").One().DotGit().Open("index")
+	c.Assert(err, IsNil)
+
+	idx := &Index{}
+	d := NewDecoder(f)
+	err = d.Decode(idx)
+	c.Assert(err, IsNil)
+
+	c.Assert(idx.Version, Equals, uint32(2))
+	c.Assert(idx.EntryCount, Equals, uint32(13))
+
+	expected := []struct {
+		Stage Stage
+		Hash  string
+	}{
+		{AncestorMode, "880cd14280f4b9b6ed3986d6671f907d7cc2a198"},
+		{OurMode, "d499a1a0b79b7d87a35155afd0c1cce78b37a91c"},
+		{TheirMode, "14f8e368114f561c38e134f6e68ea6fea12d77ed"},
+	}
+
+	// stagged files
+	for i, e := range idx.Entries[4:7] {
+		c.Assert(e.Stage, Equals, expected[i].Stage)
+		c.Assert(e.CreatedAt.Unix(), Equals, int64(0))
+		c.Assert(e.CreatedAt.Nanosecond(), Equals, 0)
+		c.Assert(e.ModifiedAt.Unix(), Equals, int64(0))
+		c.Assert(e.ModifiedAt.Nanosecond(), Equals, 0)
+		c.Assert(e.Dev, Equals, uint32(0))
+		c.Assert(e.Inode, Equals, uint32(0))
+		c.Assert(e.UID, Equals, uint32(0))
+		c.Assert(e.GID, Equals, uint32(0))
+		c.Assert(e.Size, Equals, uint32(0))
+		c.Assert(e.Hash.String(), Equals, expected[i].Hash)
+		c.Assert(e.Name, Equals, "go/example.go")
+	}
+
+}
+
+func (s *IdxfileSuite) TestDecodeExtendedV3(c *C) {
+	f, err := fixtures.Basic().ByTag("intent-to-add").One().DotGit().Open("index")
+	c.Assert(err, IsNil)
+
+	idx := &Index{}
+	d := NewDecoder(f)
+	err = d.Decode(idx)
+	c.Assert(err, IsNil)
+
+	c.Assert(idx.Version, Equals, uint32(3))
+	c.Assert(idx.EntryCount, Equals, uint32(11))
+
+	c.Assert(idx.Entries[6].Name, Equals, "intent-to-add")
+	c.Assert(idx.Entries[6].IntentToAdd, Equals, true)
+	c.Assert(idx.Entries[6].SkipWorktree, Equals, false)
+}
+
+func (s *IdxfileSuite) TestDecodeResolveUndo(c *C) {
+	f, err := fixtures.Basic().ByTag("resolve-undo").One().DotGit().Open("index")
+	c.Assert(err, IsNil)
+
+	idx := &Index{}
+	d := NewDecoder(f)
+	err = d.Decode(idx)
+	c.Assert(err, IsNil)
+
+	c.Assert(idx.Version, Equals, uint32(2))
+	c.Assert(idx.EntryCount, Equals, uint32(8))
+
+	ru := idx.ResolveUndo
+	c.Assert(ru.Entries, HasLen, 2)
+	c.Assert(ru.Entries[0].Path, Equals, "go/example.go")
+	c.Assert(ru.Entries[0].Stages, HasLen, 3)
+	c.Assert(ru.Entries[0].Stages[AncestorMode], Not(Equals), core.ZeroHash)
+	c.Assert(ru.Entries[0].Stages[OurMode], Not(Equals), core.ZeroHash)
+	c.Assert(ru.Entries[0].Stages[TheirMode], Not(Equals), core.ZeroHash)
+	c.Assert(ru.Entries[1].Path, Equals, "haskal/haskal.hs")
+	c.Assert(ru.Entries[1].Stages, HasLen, 2)
+	c.Assert(ru.Entries[1].Stages[OurMode], Not(Equals), core.ZeroHash)
+	c.Assert(ru.Entries[1].Stages[TheirMode], Not(Equals), core.ZeroHash)
+}
+
+func (s *IdxfileSuite) TestDecodeV4(c *C) {
+	f, err := fixtures.Basic().ByTag("index-v4").One().DotGit().Open("index")
+	c.Assert(err, IsNil)
+
+	idx := &Index{}
+	d := NewDecoder(f)
+	err = d.Decode(idx)
+	c.Assert(err, IsNil)
+
+	c.Assert(idx.Version, Equals, uint32(4))
+	c.Assert(idx.EntryCount, Equals, uint32(11))
+
+	names := []string{
+		".gitignore", "CHANGELOG", "LICENSE", "binary.jpg", "go/example.go",
+		"haskal/haskal.hs", "intent-to-add", "json/long.json",
+		"json/short.json", "php/crappy.php", "vendor/foo.go",
+	}
+
+	for i, e := range idx.Entries {
+		c.Assert(e.Name, Equals, names[i])
+	}
+
+	c.Assert(idx.Entries[6].Name, Equals, "intent-to-add")
+	c.Assert(idx.Entries[6].IntentToAdd, Equals, true)
+	c.Assert(idx.Entries[6].SkipWorktree, Equals, false)
+}