Wrap MergeBases

While here, test MergeBase as well.

merge.go

@@ -10,6 +10,7 @@ extern git_annotated_commit* _go_git_annotated_commit_array_get(git_annotated_co
 */
 import "C"
 import (
+	"reflect"
 	"runtime"
 	"unsafe"
 )
@@ -243,6 +244,36 @@ func (r *Repository) MergeBase(one *Oid, two *Oid) (*Oid, error) {
 	return newOidFromC(&oid), nil
 }
 
+// MergeBases retrieves the list of merge bases between two commits.
+//
+// If none are found, an empty slice is returned and the error is set
+// approprately
+func (r *Repository) MergeBases(one, two *Oid) ([]*Oid, error) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	var coids C.git_oidarray
+	ret := C.git_merge_bases(&coids, r.ptr, one.toC(), two.toC())
+	if ret < 0 {
+		return make([]*Oid, 0), MakeGitError(ret)
+	}
+
+	oids := make([]*Oid, coids.count)
+	hdr := reflect.SliceHeader {
+		Data: uintptr(unsafe.Pointer(coids.ids)),
+		Len: int(coids.count),
+		Cap: int(coids.count),
+	}
+
+	goSlice := *(*[]C.git_oid)(unsafe.Pointer(&hdr))
+
+	for i, cid := range goSlice {
+		oids[i] = newOidFromC(&cid)
+	}
+
+	return oids, nil
+}
+
 //TODO: int git_merge_base_many(git_oid *out, git_repository *repo, size_t length, const git_oid input_array[]);
 //TODO: GIT_EXTERN(int) git_merge_base_octopus(git_oid *out,git_repository *repo,size_t length,const git_oid input_array[]);
 

merge_test.go

@@ -2,6 +2,7 @@ package git
 
 import (
 	"testing"
+	"time"
 )
 
 func TestMergeWithSelf(t *testing.T) {
@@ -88,6 +89,64 @@ func TestMergeTreesWithoutAncestor(t *testing.T) {
 
 }
 
+func appendCommit(t *testing.T, repo *Repository) (*Oid, *Oid) {
+	loc, err := time.LoadLocation("Europe/Berlin")
+	checkFatal(t, err)
+	sig := &Signature{
+		Name:  "Rand Om Hacker",
+		Email: "random@hacker.com",
+		When:  time.Date(2013, 03, 06, 14, 30, 0, 0, loc),
+	}
+
+	idx, err := repo.Index()
+	checkFatal(t, err)
+	err = idx.AddByPath("README")
+	checkFatal(t, err)
+	treeId, err := idx.WriteTree()
+	checkFatal(t, err)
+
+	message := "This is another commit\n"
+	tree, err := repo.LookupTree(treeId)
+	checkFatal(t, err)
+
+	ref, err := repo.LookupReference("HEAD")
+	checkFatal(t, err)
+
+	parent, err := ref.Peel(ObjectCommit)
+	checkFatal(t, err)
+
+	commitId, err := repo.CreateCommit("HEAD", sig, sig, message, tree, parent.(*Commit))
+	checkFatal(t, err)
+
+	return commitId, treeId
+}
+
+func TestMergeBase(t *testing.T) {
+	repo := createTestRepo(t)
+	defer cleanupTestRepo(t, repo)
+
+	commitAId, _ := seedTestRepo(t, repo)
+	commitBId, _ := appendCommit(t, repo)
+
+	mergeBase, err := repo.MergeBase(commitAId, commitBId)
+	checkFatal(t, err)
+
+	if mergeBase.Cmp(commitAId) != 0 {
+		t.Fatalf("unexpected merge base")
+	}
+
+	mergeBases, err := repo.MergeBases(commitAId, commitBId)
+	checkFatal(t, err)
+
+	if len(mergeBases) != 1 {
+		t.Fatalf("expected merge bases len to be 1, got %v", len(mergeBases))
+	}
+
+	if mergeBases[0].Cmp(commitAId) != 0 {
+		t.Fatalf("unexpected merge base")
+	}
+}
+
 func compareBytes(t *testing.T, expected, actual []byte) {
 	for i, v := range expected {
 		if actual[i] != v {