git/odb: make Tree and WriteTree accessible from ObjectDatabase

git/odb/object_db.go

@@ -32,6 +32,16 @@ func (o *ObjectDatabase) Blob(sha []byte) (*Blob, error) {
 	return &b, nil
 }
 
+// Tree returns a *Tree as identified by the SHA given, or an error if one was
+// encountered.
+func (o *ObjectDatabase) Tree(sha []byte) (*Tree, error) {
+	var t Tree
+	if err := o.decode(sha, &t); err != nil {
+		return nil, err
+	}
+	return &t, nil
+}
+
 // WriteBlob stores a *Blob on disk and returns the SHA it is uniquely
 // identified by, or an error if one was encountered.
 func (o *ObjectDatabase) WriteBlob(b *Blob) ([]byte, error) {
@@ -48,6 +58,16 @@ func (o *ObjectDatabase) WriteBlob(b *Blob) ([]byte, error) {
 	return sha, nil
 }
 
+// WriteTree stores a *Tree on disk and returns the SHA it is uniquely
+// identified by, or an error if one was encountered.
+func (o *ObjectDatabase) WriteTree(t *Tree) ([]byte, error) {
+	sha, _, err := o.encode(t)
+	if err != nil {
+		return nil, err
+	}
+	return sha, nil
+}
+
 // encode encodes and saves an object to the storage backend and uses an
 // in-memory buffer to calculate the object's encoded body.
 func (d *ObjectDatabase) encode(object Object) (sha []byte, n int, err error) {

git/odb/object_db_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestDecodeBlob(t *testing.T) {
@@ -38,6 +39,39 @@ func TestDecodeBlob(t *testing.T) {
 	assert.Equal(t, contents, string(got))
 }
 
+func TestDecodeTree(t *testing.T) {
+	sha := "fcb545d5746547a597811b7441ed8eba307be1ff"
+	hexSha, err := hex.DecodeString(sha)
+	require.Nil(t, err)
+
+	blobSha := "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"
+	hexBlobSha, err := hex.DecodeString(blobSha)
+	require.Nil(t, err)
+
+	var buf bytes.Buffer
+
+	zw := zlib.NewWriter(&buf)
+	fmt.Fprintf(zw, "tree 37\x00")
+	fmt.Fprintf(zw, "100644 hello.txt\x00")
+	zw.Write(hexBlobSha)
+	zw.Close()
+
+	odb := &ObjectDatabase{s: NewMemoryStorer(map[string]io.ReadWriter{
+		sha: &buf,
+	})}
+
+	tree, err := odb.Tree(hexSha)
+
+	assert.Nil(t, err)
+	require.Equal(t, 1, len(tree.Entries))
+	assert.Equal(t, &TreeEntry{
+		Name:     "hello.txt",
+		Type:     BlobObjectType,
+		Oid:      hexBlobSha,
+		Filemode: 0100644,
+	}, tree.Entries[0])
+}
+
 func TestWriteBlob(t *testing.T) {
 	fs := NewMemoryStorer(make(map[string]io.ReadWriter))
 	odb := &ObjectDatabase{s: fs}
@@ -53,3 +87,27 @@ func TestWriteBlob(t *testing.T) {
 	assert.Equal(t, expected, hex.EncodeToString(sha))
 	assert.NotNil(t, fs.fs[hex.EncodeToString(sha)])
 }
+
+func TestWriteTree(t *testing.T) {
+	fs := NewMemoryStorer(make(map[string]io.ReadWriter))
+	odb := &ObjectDatabase{s: fs}
+
+	blobSha := "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"
+	hexBlobSha, err := hex.DecodeString(blobSha)
+	require.Nil(t, err)
+
+	sha, err := odb.WriteTree(&Tree{Entries: []*TreeEntry{
+		{
+			Name:     "hello.txt",
+			Type:     BlobObjectType,
+			Oid:      hexBlobSha,
+			Filemode: 0100644,
+		},
+	}})
+
+	expected := "fcb545d5746547a597811b7441ed8eba307be1ff"
+
+	assert.Nil(t, err)
+	assert.Equal(t, expected, hex.EncodeToString(sha))
+	assert.NotNil(t, fs.fs[hex.EncodeToString(sha)])
+}