remote: add support for ls-remote

Author: darkowlzz

remote.go

@@ -728,6 +728,39 @@ func (r *Remote) buildFetchedTags(refs memory.ReferenceStorage) (updated bool, e
 	return
 }
 
+// LSRemote performs ls-remote on the remote.
+func (r *Remote) LSRemote(auth transport.AuthMethod) ([]*plumbing.Reference, error) {
+	s, err := newUploadPackSession(r.c.URLs[0], auth)
+	if err != nil {
+		return nil, err
+	}
+
+	defer ioutil.CheckClose(s, &err)
+
+	ar, err := s.AdvertisedReferences()
+	if err != nil {
+		return nil, err
+	}
+
+	allRefs, err := ar.AllReferences()
+	if err != nil {
+		return nil, err
+	}
+
+	refs, err := allRefs.IterReferences()
+	if err != nil {
+		return nil, err
+	}
+
+	var resultRefs []*plumbing.Reference
+	refs.ForEach(func(ref *plumbing.Reference) error {
+		resultRefs = append(resultRefs, ref)
+		return nil
+	})
+
+	return resultRefs, nil
+}
+
 func objectsToPush(commands []*packp.Command) ([]plumbing.Hash, error) {
 	var objects []plumbing.Hash
 	for _, cmd := range commands {

remote_test.go

@@ -11,6 +11,7 @@ import (
 	"gopkg.in/src-d/go-git.v4/config"
 	"gopkg.in/src-d/go-git.v4/plumbing"
 	"gopkg.in/src-d/go-git.v4/plumbing/storer"
+	"gopkg.in/src-d/go-git.v4/plumbing/transport"
 	"gopkg.in/src-d/go-git.v4/storage"
 	"gopkg.in/src-d/go-git.v4/storage/filesystem"
 	"gopkg.in/src-d/go-git.v4/storage/memory"
@@ -642,3 +643,41 @@ func (s *RemoteSuite) TestGetHaves(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(l, HasLen, 2)
 }
+
+func (s *RemoteSuite) TestLSRemote(c *C) {
+	url := c.MkDir()
+	server, err := PlainInit(url, true)
+	c.Assert(err, IsNil)
+
+	srcFs := fixtures.Basic().One().DotGit()
+	sto, err := filesystem.NewStorage(srcFs)
+	c.Assert(err, IsNil)
+
+	remote := newRemote(sto, &config.RemoteConfig{
+		Name: DefaultRemoteName,
+		URLs: []string{url},
+	})
+
+	rs := config.RefSpec("refs/heads/*:refs/heads/*")
+	err = remote.Push(&PushOptions{
+		RefSpecs: []config.RefSpec{rs},
+	})
+	c.Assert(err, IsNil)
+
+	// Perform ls-remote.
+	var authMethod transport.AuthMethod
+	refs, err := remote.LSRemote(authMethod)
+	c.Assert(err, IsNil)
+
+	// Create a map of remote name and their hash.
+	refsMap := map[string]string{}
+	for _, rf := range refs {
+		// Skip the symbolically linked HEAD.
+		if string(rf.Name()) == "HEAD" {
+			continue
+		}
+		refsMap[string(rf.Name())] = rf.Hash().String()
+	}
+
+	AssertReferences(c, server, refsMap)
+}