Improve delta reutilization

- Remove wrong 'if' on delta selector that causes poor delta reutilizations
- packfile.Encoder now can write deltas and objects in a non specific order
- ObjectToPack now saves the Offset on the packfile to be able to obtain base
offset in a recursive manner and write them before the delta itself
- Added encoder test to check cyclic delta chains
- Check the output packfile hash in all encoder tests

Signed-off-by: Antonio Jesus Navarro Perez <antnavper@gmail.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/plumbing/format/packfile/encoder_advanced_test.go b/plumbing/format/packfile/encoder_advanced_test.go
index 69d6b39..1075875 100644
--- a/plumbing/format/packfile/encoder_advanced_test.go
+++ b/plumbing/format/packfile/encoder_advanced_test.go
@@ -68,16 +68,18 @@ func (s *EncoderAdvancedSuite) testEncodeDecode(c *C, storage storer.Storer, pac
 
 	buf := bytes.NewBuffer(nil)
 	enc := NewEncoder(buf, storage, false)
-	_, err = enc.Encode(hashes, packWindow)
+	encodeHash, err := enc.Encode(hashes, packWindow)
 	c.Assert(err, IsNil)
 
 	scanner := NewScanner(buf)
 	storage = memory.NewStorage()
 	d, err := NewDecoder(scanner, storage)
 	c.Assert(err, IsNil)
-	_, err = d.Decode()
+	decodeHash, err := d.Decode()
 	c.Assert(err, IsNil)
 
+	c.Assert(encodeHash, Equals, decodeHash)
+
 	objIter, err = storage.IterEncodedObjects(plumbing.AnyObject)
 	c.Assert(err, IsNil)
 	obtainedObjects := map[plumbing.Hash]bool{}