Compute checked out branch at runtime

private/buf/bufsync/commits_to_sync_test.go

@@ -35,7 +35,8 @@ func TestCommitsToSyncWithNoPreviousSyncPoints(t *testing.T) {
 	require.NoError(t, err)
 	const defaultBranchName = "main"
 	repo, repoDir := scaffoldGitRepository(t, defaultBranchName)
-	prepareGitRepoSyncWithNoPreviousSyncPoints(t, repoDir, moduleIdentityInHEAD, defaultBranchName)
+	runner := command.NewRunner()
+	prepareGitRepoSyncWithNoPreviousSyncPoints(t, runner, repoDir, moduleIdentityInHEAD, defaultBranchName)
 	type testCase struct {
 		name            string
 		branch          string
@@ -63,20 +64,20 @@ func TestCommitsToSyncWithNoPreviousSyncPoints(t *testing.T) {
 			expectedCommits: 1,
 		},
 	}
+	handler := newMockSyncHandler() // use same handler for all test cases
 	for _, withOverride := range []bool{false, true} {
 		for _, tc := range testCases {
 			func(tc testCase) {
 				t.Run(fmt.Sprintf("%s/override_%t", tc.name, withOverride), func(t *testing.T) {
+					// check out the branch to sync
+					runInDir(t, runner, repoDir, "git", "checkout", tc.branch)
 					const moduleDir = "."
-					opts := []bufsync.SyncerOption{
-						bufsync.SyncerWithAllBranches(),
-					}
+					var opts []bufsync.SyncerOption
 					if withOverride {
 						opts = append(opts, bufsync.SyncerWithModule(moduleDir, moduleIdentityOverride))
 					} else {
 						opts = append(opts, bufsync.SyncerWithModule(moduleDir, nil))
 					}
-					handler := newMockSyncHandler()
 					syncer, err := bufsync.NewSyncer(
 						zaptest.NewLogger(t),
 						bufsync.NewRealClock(),
@@ -101,8 +102,13 @@ func TestCommitsToSyncWithNoPreviousSyncPoints(t *testing.T) {
 // | o-o----------o-----------------o (master)
 // |   └o-o (foo) └o--------o (bar)
 // |               └o (baz)
-func prepareGitRepoSyncWithNoPreviousSyncPoints(t *testing.T, repoDir string, moduleIdentity bufmoduleref.ModuleIdentity, defaultBranchName string) {
-	runner := command.NewRunner()
+func prepareGitRepoSyncWithNoPreviousSyncPoints(
+	t *testing.T,
+	runner command.Runner,
+	repoDir string,
+	moduleIdentity bufmoduleref.ModuleIdentity,
+	defaultBranchName string,
+) {
 	var allBranches = []string{defaultBranchName, "foo", "bar", "baz"}
 
 	var commitsCounter int

private/buf/bufsync/syncer.go

@@ -184,7 +184,10 @@ func (s *syncer) prepareSync(ctx context.Context) error {
 		branchesToSync = stringutil.MapToSlice(allBranches)
 	} else {
 		// sync current branch, make sure it's present
-		currentBranch := s.repo.CurrentBranch()
+		currentBranch, err := s.repo.CurrentBranch(ctx)
+		if err != nil {
+			return fmt.Errorf("determine checked out branch")
+		}
 		if _, currentBranchPresent := allBranches[currentBranch]; !currentBranchPresent {
 			return fmt.Errorf("current branch %s is not present %s", currentBranch, remoteErrMsg)
 		}

private/pkg/git/git.go

@@ -272,7 +272,7 @@ type Repository interface {
 	// remote named `origin`). It can be customized via the `OpenRepositoryWithDefaultBranch` option.
 	DefaultBranch() string
 	// CurrentBranch is the current checked out branch.
-	CurrentBranch() string
+	CurrentBranch(ctx context.Context) (string, error)
 	// ForEachBranch ranges over branches in the repository in an undefined order.
 	ForEachBranch(f func(branch string, headHash Hash) error, options ...ForEachBranchOption) error
 	// ForEachCommit ranges over commits in reverse topological order, going backwards in time always

private/pkg/git/repository.go

@@ -35,10 +35,10 @@ type openRepositoryOpts struct {
 }
 
 type repository struct {
-	gitDirPath       string
-	defaultBranch    string
-	checkedOutBranch string
-	objectReader     *objectReader
+	gitDirPath    string
+	defaultBranch string
+	objectReader  *objectReader
+	runner        command.Runner
 
 	// packedOnce controls the fields below related to reading the `packed-refs` file
 	packedOnce      sync.Once
@@ -77,15 +77,11 @@ func openGitRepository(
 			return nil, fmt.Errorf("automatically determine default branch: %w", err)
 		}
 	}
-	checkedOutBranch, err := detectCheckedOutBranch(ctx, gitDirPath, runner)
-	if err != nil {
-		return nil, fmt.Errorf("automatically determine checked out branch: %w", err)
-	}
 	return &repository{
-		gitDirPath:       gitDirPath,
-		defaultBranch:    opts.defaultBranch,
-		checkedOutBranch: checkedOutBranch,
-		objectReader:     reader,
+		gitDirPath:    gitDirPath,
+		defaultBranch: opts.defaultBranch,
+		objectReader:  reader,
+		runner:        runner,
 	}, nil
 }
 
@@ -157,8 +153,8 @@ func (r *repository) DefaultBranch() string {
 	return r.defaultBranch
 }
 
-func (r *repository) CurrentBranch() string {
-	return r.checkedOutBranch
+func (r *repository) CurrentBranch(ctx context.Context) (string, error) {
+	return detectCheckedOutBranch(ctx, r.gitDirPath, r.runner)
 }
 
 func (r *repository) ForEachCommit(f func(Commit) error, options ...ForEachCommitOption) error {

private/pkg/git/repository_test.go

@@ -15,6 +15,7 @@
 package git_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/bufbuild/buf/private/pkg/git"
@@ -235,9 +236,11 @@ func TestForEachBranch(t *testing.T) {
 			t.Run(tc.name, func(t *testing.T) {
 				t.Parallel()
 				repo := gittest.ScaffoldGitRepository(t)
-				assert.Equal(t, gittest.DefaultBranch, repo.CurrentBranch())
+				currentBranch, err := repo.CurrentBranch(context.Background())
+				require.NoError(t, err)
+				assert.Equal(t, gittest.DefaultBranch, currentBranch)
 				branches := make(map[string]struct{})
-				err := repo.ForEachBranch(func(branch string, headHash git.Hash) error {
+				err = repo.ForEachBranch(func(branch string, headHash git.Hash) error {
 					require.NotEmpty(t, branch)
 					if _, alreadySeen := branches[branch]; alreadySeen {
 						assert.Fail(t, "duplicate branch", branch)