feat(cli): implement exec and exec_all commands

internal/homesick/core/core.go

@@ -219,6 +219,75 @@ func (a *App) Open(castle string) error {
 	return nil
 }
 
+func (a *App) Exec(castle string, command []string) error {
+	commandString := strings.TrimSpace(strings.Join(command, " "))
+	if commandString == "" {
+		return errors.New("exec requires COMMAND")
+	}
+
+	castleRoot := filepath.Join(a.ReposDir, castle)
+	if _, err := os.Stat(castleRoot); err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return fmt.Errorf("castle %q not found", castle)
+		}
+		return err
+	}
+
+	cmd := exec.Command("sh", "-c", commandString)
+	cmd.Dir = castleRoot
+	cmd.Stdout = a.Stdout
+	cmd.Stderr = a.Stderr
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("exec failed: %w", err)
+	}
+
+	return nil
+}
+
+func (a *App) ExecAll(command []string) error {
+	commandString := strings.TrimSpace(strings.Join(command, " "))
+	if commandString == "" {
+		return errors.New("exec_all requires COMMAND")
+	}
+
+	if _, err := os.Stat(a.ReposDir); err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return nil
+		}
+		return err
+	}
+
+	var castles []string
+	err := filepath.WalkDir(a.ReposDir, func(path string, d fs.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+		if !d.IsDir() || d.Name() != ".git" {
+			return nil
+		}
+
+		castleRoot := filepath.Dir(path)
+		rel, err := filepath.Rel(a.ReposDir, castleRoot)
+		if err != nil {
+			return err
+		}
+		castles = append(castles, rel)
+		return filepath.SkipDir
+	})
+	if err != nil {
+		return err
+	}
+
+	sort.Strings(castles)
+	for _, castle := range castles {
+		if err := a.Exec(castle, []string{commandString}); err != nil {
+			return fmt.Errorf("exec_all failed for %q: %w", castle, err)
+		}
+	}
+
+	return nil
+}
+
 func (a *App) Generate(castlePath string) error {
 	trimmed := strings.TrimSpace(castlePath)
 	if trimmed == "" {

internal/homesick/core/exec_test.go

@@ -0,0 +1,79 @@
+package core_test
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"git.hrafn.xyz/aether/gosick/internal/homesick/core"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+)
+
+type ExecSuite struct {
+	suite.Suite
+	tmpDir   string
+	homeDir  string
+	reposDir string
+	stdout   *bytes.Buffer
+	stderr   *bytes.Buffer
+	app      *core.App
+}
+
+func TestExecSuite(t *testing.T) {
+	suite.Run(t, new(ExecSuite))
+}
+
+func (s *ExecSuite) SetupTest() {
+	s.tmpDir = s.T().TempDir()
+	s.homeDir = filepath.Join(s.tmpDir, "home")
+	s.reposDir = filepath.Join(s.homeDir, ".homesick", "repos")
+	require.NoError(s.T(), os.MkdirAll(s.reposDir, 0o755))
+
+	s.stdout = &bytes.Buffer{}
+	s.stderr = &bytes.Buffer{}
+	s.app = &core.App{
+		HomeDir:  s.homeDir,
+		ReposDir: s.reposDir,
+		Stdout:   s.stdout,
+		Stderr:   s.stderr,
+	}
+}
+
+func (s *ExecSuite) createCastle(name string) string {
+	castleRoot := filepath.Join(s.reposDir, name)
+	require.NoError(s.T(), os.MkdirAll(castleRoot, 0o755))
+	return castleRoot
+}
+
+func (s *ExecSuite) TestExec_UnknownCastleReturnsError() {
+	err := s.app.Exec("nonexistent", []string{"pwd"})
+	require.Error(s.T(), err)
+	require.Contains(s.T(), err.Error(), "not found")
+}
+
+func (s *ExecSuite) TestExec_RunsCommandInCastleRoot() {
+	castleRoot := s.createCastle("dotfiles")
+
+	require.NoError(s.T(), s.app.Exec("dotfiles", []string{"pwd"}))
+	require.Contains(s.T(), s.stdout.String(), castleRoot)
+}
+
+func (s *ExecSuite) TestExec_ForwardsStdoutAndStderr() {
+	s.createCastle("dotfiles")
+
+	require.NoError(s.T(), s.app.Exec("dotfiles", []string{"echo out && echo err >&2"}))
+	require.Contains(s.T(), s.stdout.String(), "out")
+	require.Contains(s.T(), s.stderr.String(), "err")
+}
+
+func (s *ExecSuite) TestExecAll_RunsCommandForEachCastle() {
+	zeta := s.createCastle("zeta")
+	alpha := s.createCastle("alpha")
+	require.NoError(s.T(), os.MkdirAll(filepath.Join(zeta, ".git"), 0o755))
+	require.NoError(s.T(), os.MkdirAll(filepath.Join(alpha, ".git"), 0o755))
+
+	require.NoError(s.T(), s.app.ExecAll([]string{"basename \"$PWD\""}))
+	require.Equal(s.T(), "alpha\nzeta\n", s.stdout.String())
+}