Implement delete ref endpoint in git service

implemented delete ref endpoint in git service for Bitbucket server.

Signed-off-by: Zaki Shaikh <zashaikh@redhat.com>

scm/driver/stash/git.go

@@ -45,7 +45,10 @@ func (s *gitService) CreateRef(ctx context.Context, repo, ref, sha string) (*scm
 }
 
 func (s *gitService) DeleteRef(ctx context.Context, repo, ref string) (*scm.Response, error) {
-	return nil, scm.ErrNotSupported
+	namespace, name := scm.Split(repo)
+	path := fmt.Sprintf("rest/branch-utils/latest/projects/%s/repos/%s/branches", namespace, name)
+	in := deleteRefInput{Name: ref}
+	return s.client.do(ctx, "DELETE", path, &in, nil)
 }
 
 func (s *gitService) FindBranch(ctx context.Context, repo, branch string) (*scm.Reference, *scm.Response, error) {
@@ -142,6 +145,11 @@ func (s *gitService) CompareCommits(ctx context.Context, repo, ref1, ref2 string
 	return convertDiffstats(out), res, err
 }
 
+type deleteRefInput struct {
+	DryRun bool   `json:"dryRun"`
+	Name   string `json:"name"`
+}
+
 type branch struct {
 	ID              string `json:"id"`
 	DisplayID       string `json:"displayId"`

scm/driver/stash/git_test.go

@@ -44,6 +44,25 @@ func TestGitFindCommit(t *testing.T) {
 	}
 }
 
+func TestGitDeleteRef(t *testing.T) {
+	defer gock.Off()
+
+	gock.New("http://example.com:7990").
+		Delete("rest/branch-utils/latest/projects/PRJ/repos/my-repo/branches").
+		Reply(204).
+		Type("application/json")
+
+	client, _ := New("http://example.com:7990")
+	resp, err := client.Git.DeleteRef(context.Background(), "PRJ/my-repo", "delete")
+	if err != nil {
+		t.Error(err)
+	}
+
+	if resp.Status != 204 {
+		t.Errorf("DeleteRef returned %v", resp.Status)
+	}
+}
+
 func TestGitFindBranch(t *testing.T) {
 	defer gock.Off()