remoterepo: Add HeadReference

HeadReference is a replacement for GetDefaultBranch. The intention
is to replace and remove the default branch heuristic that
GetDefaultBranch uses and instead rely solely on HEAD.

This could have been implemented as a parameter on GetDefaultBranch but
this requires modifying all call sites and localrepo already has a
method called HeadReference for this purpose.

4 files changed, 80 insertions, 1 deletions

diff --git a/internal/git/gittest/repository_suite.go b/internal/git/gittest/repository_suite.go
index f9c64c293..d7310da5c 100644
--- a/internal/git/gittest/repository_suite.go
+++ b/internal/git/gittest/repository_suite.go
@@ -33,6 +33,10 @@ func TestRepository(t *testing.T, cfg config.Cfg, getRepository GetRepositoryFun
 			desc: "GetDefaultBranch",
 			test: testRepositoryGetDefaultBranch,
 		},
+		{
+			desc: "HeadReference",
+			test: testRepositoryHeadReference,
+		},
 	} {
 		t.Run(tc.desc, func(t *testing.T) {
 			tc.test(t, cfg, getRepository)
@@ -190,3 +194,60 @@ func testRepositoryGetDefaultBranch(t *testing.T, cfg config.Cfg, getRepository
 		})
 	}
 }
+
+func testRepositoryHeadReference(t *testing.T, cfg config.Cfg, getRepository GetRepositoryFunc) {
+	t.Parallel()
+	ctx := testhelper.Context(t)
+
+	for _, tc := range []struct {
+		desc         string
+		repo         func(t *testing.T) git.Repository
+		expectedName git.ReferenceName
+	}{
+		{
+			desc: "default unborn",
+			repo: func(t *testing.T) git.Repository {
+				repo, _ := getRepository(t, ctx)
+				return repo
+			},
+			expectedName: git.DefaultRef,
+		},
+		{
+			desc: "default exists",
+			repo: func(t *testing.T) git.Repository {
+				repo, repoPath := getRepository(t, ctx)
+				WriteCommit(t, cfg, repoPath, WithBranch(git.DefaultBranch))
+				return repo
+			},
+			expectedName: git.DefaultRef,
+		},
+		{
+			desc: "HEAD set nonexistent",
+			repo: func(t *testing.T) git.Repository {
+				repo, repoPath := getRepository(t, ctx)
+				Exec(t, cfg, "-C", repoPath, "symbolic-ref", "HEAD", "refs/heads/feature")
+				return repo
+			},
+			expectedName: git.NewReferenceNameFromBranchName("feature"),
+		},
+		{
+			desc: "HEAD set exists",
+			repo: func(t *testing.T) git.Repository {
+				repo, repoPath := getRepository(t, ctx)
+				WriteCommit(t, cfg, repoPath, WithBranch("feature"))
+				Exec(t, cfg, "-C", repoPath, "symbolic-ref", "HEAD", "refs/heads/feature")
+				return repo
+			},
+			expectedName: git.NewReferenceNameFromBranchName("feature"),
+		},
+	} {
+		tc := tc
+
+		t.Run(tc.desc, func(t *testing.T) {
+			t.Parallel()
+			name, err := tc.repo(t).HeadReference(ctx)
+			require.NoError(t, err)
+			require.Equal(t, tc.expectedName, name)
+		})
+	}
+}
diff --git a/internal/git/remoterepo/repository.go b/internal/git/remoterepo/repository.go
index a7d946cd8..4b1f2eb8b 100644
--- a/internal/git/remoterepo/repository.go
+++ b/internal/git/remoterepo/repository.go
@@ -113,3 +113,18 @@ func (rr *Repo) GetDefaultBranch(ctx context.Context) (git.ReferenceName, error)
 
 	return git.ReferenceName(resp.Name), nil
 }
+
+// HeadReference returns the reference that HEAD points to for the remote
+// repository.
+func (rr *Repo) HeadReference(ctx context.Context) (git.ReferenceName, error) {
+	resp, err := gitalypb.NewRefServiceClient(rr.conn).FindDefaultBranchName(
+		ctx, &gitalypb.FindDefaultBranchNameRequest{
+			Repository: rr.Repository,
+			HeadOnly:   true,
+		})
+	if err != nil {
+		return "", err
+	}
+
+	return git.ReferenceName(resp.Name), nil
+}
diff --git a/internal/git/remoterepo/repository_test.go b/internal/git/remoterepo/repository_test.go
index 61edd5f83..21fcab898 100644
--- a/internal/git/remoterepo/repository_test.go
+++ b/internal/git/remoterepo/repository_test.go
@@ -26,7 +26,7 @@ func TestRepository(t *testing.T) {
 	cfg := setupGitalyServer(t)
 
 	pool := client.NewPool()
-	defer pool.Close()
+	t.Cleanup(func() { testhelper.MustClose(t, pool) })
 
 	gittest.TestRepository(t, cfg, func(tb testing.TB, ctx context.Context) (git.Repository, string) {
 		tb.Helper()
diff --git a/internal/git/repository.go b/internal/git/repository.go
index b3cf9725f..fe999d9ac 100644
--- a/internal/git/repository.go
+++ b/internal/git/repository.go
@@ -49,6 +49,9 @@ type Repository interface {
 	HasBranches(ctx context.Context) (bool, error)
 	// GetDefaultBranch returns the default branch of the repository.
 	GetDefaultBranch(ctx context.Context) (ReferenceName, error)
+	// HeadReference returns the reference that HEAD points to for the
+	// repository.
+	HeadReference(ctx context.Context) (ReferenceName, error)
 }
 
 // RepositoryExecutor is an interface which allows execution of Git commands in a specific