repo set-default: support bare git repos

The command was using this to check for git repo context:

    git rev-parse --is-inside-work-tree

With this change, this is used instead:

    git rev-parse --git-dir

The latter approach works in the context of a bare git repository, which does not have a worktree.

git/client.go

@@ -20,6 +20,10 @@ import (
 
 var remoteRE = regexp.MustCompile(`(.+)\s+(.+)\s+\((push|fetch)\)`)
 
+type errWithExitCode interface {
+	ExitCode() int
+}
+
 type Client struct {
 	GhPath  string
 	RepoDir string
@@ -489,21 +493,16 @@ func (c *Client) AddRemote(ctx context.Context, name, urlStr string, trackingBra
 	return remote, nil
 }
 
-func (c *Client) InGitDirectory(ctx context.Context) bool {
-	showCmd, err := c.Command(ctx, "rev-parse", "--is-inside-work-tree")
-	if err != nil {
-		return false
-	}
-	out, err := showCmd.Output()
+func (c *Client) IsLocalGitRepo(ctx context.Context) (bool, error) {
+	_, err := c.GitDir(ctx)
 	if err != nil {
-		return false
-	}
-
-	split := strings.Split(string(out), "\n")
-	if len(split) > 0 {
-		return split[0] == "true"
+		var execError errWithExitCode
+		if errors.As(err, &execError) && execError.ExitCode() == 128 {
+			return false, nil
+		}
+		return false, err
 	}
-	return false
+	return true, nil
 }
 
 func (c *Client) UnsetRemoteResolution(ctx context.Context, name string) error {

internal/run/stub.go

@@ -106,18 +106,36 @@ type commandStub struct {
 	callbacks  []CommandCallback
 }
 
+type errWithExitCode struct {
+	message  string
+	exitCode int
+}
+
+func (e errWithExitCode) Error() string {
+	return e.message
+}
+
+func (e errWithExitCode) ExitCode() int {
+	return e.exitCode
+}
+
 // Run satisfies Runnable
 func (s *commandStub) Run() error {
 	if s.exitStatus != 0 {
-		return fmt.Errorf("%s exited with status %d", s.pattern, s.exitStatus)
+		// It's nontrivial to construct a fake `exec.ExitError` instance, so we return an error type
+		// that has the `ExitCode() int` method.
+		return errWithExitCode{
+			message:  fmt.Sprintf("%s exited with status %d", s.pattern, s.exitStatus),
+			exitCode: s.exitStatus,
+		}
 	}
 	return nil
 }
 
 // Output satisfies Runnable
 func (s *commandStub) Output() ([]byte, error) {
-	if s.exitStatus != 0 {
-		return []byte(nil), fmt.Errorf("%s exited with status %d", s.pattern, s.exitStatus)
+	if err := s.Run(); err != nil {
+		return []byte(nil), err
 	}
 	return []byte(s.stdout), nil
 }

pkg/cmd/repo/setdefault/setdefault.go

@@ -90,9 +90,9 @@ func NewCmdSetDefault(f *cmdutil.Factory, runF func(*SetDefaultOptions) error) *
 				return cmdutil.FlagErrorf("repository required when not running interactively")
 			}
 
-			c := &git.Client{}
-
-			if !c.InGitDirectory(ctx.Background()) {
+			if isLocal, err := opts.GitClient.IsLocalGitRepo(cmd.Context()); err != nil {
+				return err
+			} else if !isLocal {
 				return errors.New("must be run from inside a git repository")
 			}
 

pkg/cmd/repo/setdefault/setdefault_test.go

@@ -29,15 +29,15 @@ func TestNewCmdSetDefault(t *testing.T) {
 		{
 			name: "no argument",
 			gitStubs: func(cs *run.CommandStubber) {
-				cs.Register(`git rev-parse --is-inside-work-tree`, 0, "true")
+				cs.Register(`git rev-parse --git-dir`, 0, ".git")
 			},
 			input:  "",
 			output: SetDefaultOptions{},
 		},
 		{
 			name: "repo argument",
 			gitStubs: func(cs *run.CommandStubber) {
-				cs.Register(`git rev-parse --is-inside-work-tree`, 0, "true")
+				cs.Register(`git rev-parse --git-dir`, 0, ".git")
 			},
 			input:  "cli/cli",
 			output: SetDefaultOptions{Repo: ghrepo.New("cli", "cli")},
@@ -52,23 +52,23 @@ func TestNewCmdSetDefault(t *testing.T) {
 		{
 			name: "view flag",
 			gitStubs: func(cs *run.CommandStubber) {
-				cs.Register(`git rev-parse --is-inside-work-tree`, 0, "true")
+				cs.Register(`git rev-parse --git-dir`, 0, ".git")
 			},
 			input:  "--view",
 			output: SetDefaultOptions{ViewMode: true},
 		},
 		{
 			name: "unset flag",
 			gitStubs: func(cs *run.CommandStubber) {
-				cs.Register(`git rev-parse --is-inside-work-tree`, 0, "true")
+				cs.Register(`git rev-parse --git-dir`, 0, ".git")
 			},
 			input:  "--unset",
 			output: SetDefaultOptions{UnsetMode: true},
 		},
 		{
 			name: "run from non-git directory",
 			gitStubs: func(cs *run.CommandStubber) {
-				cs.Register(`git rev-parse --is-inside-work-tree`, 1, "")
+				cs.Register(`git rev-parse --git-dir`, 128, "")
 			},
 			input:   "",
 			wantErr: true,
@@ -83,6 +83,7 @@ func TestNewCmdSetDefault(t *testing.T) {
 		io.SetStderrTTY(true)
 		f := &cmdutil.Factory{
 			IOStreams: io,
+			GitClient: &git.Client{GitPath: "/fake/path/to/git"},
 		}
 
 		var gotOpts *SetDefaultOptions