2 files changed, 107 insertions, 10 deletions

diff --git a/plumbing/format/idxfile/idxfile_test.go b/plumbing/format/idxfile/idxfile_test.go
index f42a419..d15accf 100644
--- a/plumbing/format/idxfile/idxfile_test.go
+++ b/plumbing/format/idxfile/idxfile_test.go
@@ -3,15 +3,22 @@ package idxfile_test
 import (
 	"bytes"
 	"encoding/base64"
+	"fmt"
 	"io"
 	"testing"
 
 	"gopkg.in/src-d/go-git.v4/plumbing"
 	"gopkg.in/src-d/go-git.v4/plumbing/format/idxfile"
+
+	. "gopkg.in/check.v1"
+	"gopkg.in/src-d/go-git-fixtures.v3"
 )
 
 func BenchmarkFindOffset(b *testing.B) {
-	idx := fixtureIndex(b)
+	idx, err := fixtureIndex()
+	if err != nil {
+		b.Fatalf(err.Error())
+	}
 
 	for i := 0; i < b.N; i++ {
 		for _, h := range fixtureHashes {
@@ -24,7 +31,10 @@ func BenchmarkFindOffset(b *testing.B) {
 }
 
 func BenchmarkFindCRC32(b *testing.B) {
-	idx := fixtureIndex(b)
+	idx, err := fixtureIndex()
+	if err != nil {
+		b.Fatalf(err.Error())
+	}
 
 	for i := 0; i < b.N; i++ {
 		for _, h := range fixtureHashes {
@@ -37,7 +47,10 @@ func BenchmarkFindCRC32(b *testing.B) {
 }
 
 func BenchmarkContains(b *testing.B) {
-	idx := fixtureIndex(b)
+	idx, err := fixtureIndex()
+	if err != nil {
+		b.Fatalf(err.Error())
+	}
 
 	for i := 0; i < b.N; i++ {
 		for _, h := range fixtureHashes {
@@ -54,7 +67,10 @@ func BenchmarkContains(b *testing.B) {
 }
 
 func BenchmarkEntries(b *testing.B) {
-	idx := fixtureIndex(b)
+	idx, err := fixtureIndex()
+	if err != nil {
+		b.Fatalf(err.Error())
+	}
 
 	for i := 0; i < b.N; i++ {
 		iter, err := idx.Entries()
@@ -82,6 +98,23 @@ func BenchmarkEntries(b *testing.B) {
 	}
 }
 
+type IndexSuite struct {
+	fixtures.Suite
+}
+
+var _ = Suite(&IndexSuite{})
+
+func (s *IndexSuite) TestFindHash(c *C) {
+	idx, err := fixtureIndex()
+	c.Assert(err, IsNil)
+
+	for i, pos := range fixtureOffsets {
+		hash, err := idx.FindHash(pos)
+		c.Assert(err, IsNil)
+		c.Assert(hash, Equals, fixtureHashes[i])
+	}
+}
+
 var fixtureHashes = []plumbing.Hash{
 	plumbing.NewHash("303953e5aa461c203a324821bc1717f9b4fff895"),
 	plumbing.NewHash("5296768e3d9f661387ccbff18c4dea6c997fd78c"),
@@ -94,7 +127,19 @@ var fixtureHashes = []plumbing.Hash{
 	plumbing.NewHash("35858be9c6f5914cbe6768489c41eb6809a2bceb"),
 }
 
-func fixtureIndex(t testing.TB) *idxfile.MemoryIndex {
+var fixtureOffsets = []int64{
+	12,
+	142,
+	1601322837,
+	2646996529,
+	3452385606,
+	3707047470,
+	5323223332,
+	5894072943,
+	5924278919,
+}
+
+func fixtureIndex() (*idxfile.MemoryIndex, error) {
 	f := bytes.NewBufferString(fixtureLarge4GB)
 
 	idx := new(idxfile.MemoryIndex)
@@ -102,8 +147,8 @@ func fixtureIndex(t testing.TB) *idxfile.MemoryIndex {
 	d := idxfile.NewDecoder(base64.NewDecoder(base64.StdEncoding, f))
 	err := d.Decode(idx)
 	if err != nil {
-		t.Fatalf("unexpected error decoding index: %s", err)
+		return nil, fmt.Errorf("unexpected error decoding index: %s", err)
 	}
 
-	return idx
+	return idx, nil
 }
diff --git a/plumbing/format/idxfile/writer_test.go b/plumbing/format/idxfile/writer_test.go
index 51273a3..780acd9 100644
--- a/plumbing/format/idxfile/writer_test.go
+++ b/plumbing/format/idxfile/writer_test.go
@@ -2,8 +2,10 @@ package idxfile_test
 
 import (
 	"bytes"
+	"encoding/base64"
 	"io/ioutil"
 
+	"gopkg.in/src-d/go-git.v4/plumbing"
 	"gopkg.in/src-d/go-git.v4/plumbing/format/idxfile"
 	"gopkg.in/src-d/go-git.v4/plumbing/format/packfile"
 
@@ -11,13 +13,13 @@ import (
 	"gopkg.in/src-d/go-git-fixtures.v3"
 )
 
-type IndexSuite struct {
+type WriterSuite struct {
 	fixtures.Suite
 }
 
-var _ = Suite(&IndexSuite{})
+var _ = Suite(&WriterSuite{})
 
-func (s *IndexSuite) TestIndexWriter(c *C) {
+func (s *WriterSuite) TestWriter(c *C) {
 	f := fixtures.Basic().One()
 	scanner := packfile.NewScanner(f.Packfile())
 
@@ -43,3 +45,53 @@ func (s *IndexSuite) TestIndexWriter(c *C) {
 
 	c.Assert(buf.Bytes(), DeepEquals, expected)
 }
+
+func (s *WriterSuite) TestWriterLarge(c *C) {
+	writer := new(idxfile.Writer)
+	err := writer.OnHeader(uint32(len(fixture4GbEntries)))
+	c.Assert(err, IsNil)
+
+	for _, o := range fixture4GbEntries {
+		err = writer.OnInflatedObjectContent(plumbing.NewHash(o.hash), o.offset, o.crc)
+		c.Assert(err, IsNil)
+	}
+
+	err = writer.OnFooter(fixture4GbChecksum)
+	c.Assert(err, IsNil)
+
+	idx, err := writer.Index()
+	c.Assert(err, IsNil)
+
+	// load fixture index
+	f := bytes.NewBufferString(fixtureLarge4GB)
+	expected, err := ioutil.ReadAll(base64.NewDecoder(base64.StdEncoding, f))
+	c.Assert(err, IsNil)
+
+	buf := new(bytes.Buffer)
+	encoder := idxfile.NewEncoder(buf)
+	n, err := encoder.Encode(idx)
+	c.Assert(err, IsNil)
+	c.Assert(n, Equals, len(expected))
+
+	c.Assert(buf.Bytes(), DeepEquals, expected)
+}
+
+var (
+	fixture4GbChecksum = plumbing.NewHash("afabc2269205cf85da1bf7e2fdff42f73810f29b")
+
+	fixture4GbEntries = []struct {
+		offset int64
+		hash   string
+		crc    uint32
+	}{
+		{12, "303953e5aa461c203a324821bc1717f9b4fff895", 0xbc347c4c},
+		{142, "5296768e3d9f661387ccbff18c4dea6c997fd78c", 0xcdc22842},
+		{1601322837, "03fc8d58d44267274edef4585eaeeb445879d33f", 0x929dfaaa},
+		{2646996529, "8f3ceb4ea4cb9e4a0f751795eb41c9a4f07be772", 0xa61def8a},
+		{3452385606, "e0d1d625010087f79c9e01ad9d8f95e1628dda02", 0x06bea180},
+		{3707047470, "90eba326cdc4d1d61c5ad25224ccbf08731dd041", 0x7193f3ba},
+		{5323223332, "bab53055add7bc35882758a922c54a874d6b1272", 0xac269b8e},
+		{5894072943, "1b8995f51987d8a449ca5ea4356595102dc2fbd4", 0x2187c056},
+		{5924278919, "35858be9c6f5914cbe6768489c41eb6809a2bceb", 0x9c89d9d2},
+	}
+)