feat: support changing work directory (#15)

Closes #10

Signed-off-by: Brian McGee <brian@bmcgee.ie>

Reviewed-on: https://git.numtide.com/numtide/treefmt/pulls/15
Reviewed-by: Jonas Chevalier <zimbatm@noreply.git.numtide.com>
Co-authored-by: Brian McGee <brian@bmcgee.ie>
Co-committed-by: Brian McGee <brian@bmcgee.ie>

internal/cli/cli.go

@@ -1,19 +1,21 @@
 package cli
 
 import (
+	"github.com/alecthomas/kong"
 	"github.com/charmbracelet/log"
 )
 
 var Cli = Options{}
 
 type Options struct {
-	AllowMissingFormatter bool     `default:"false" help:"Do not exit with error if a configured formatter is missing"`
-	ClearCache            bool     `short:"c" help:"Reset the evaluation cache. Use in case the cache is not precise enough"`
-	ConfigFile            string   `type:"existingfile" default:"./treefmt.toml"`
-	FailOnChange          bool     `help:"Exit with error if any changes were made. Useful for CI"`
-	Formatters            []string `help:"Specify formatters to apply. Defaults to all formatters"`
-	TreeRoot              string   `type:"existingdir" default:"."`
-	Verbosity             int      `name:"verbose" short:"v" type:"counter" default:"0" env:"LOG_LEVEL" help:"Set the verbosity of logs e.g. -vv"`
+	AllowMissingFormatter bool               `default:"false" help:"Do not exit with error if a configured formatter is missing"`
+	WorkingDirectory      kong.ChangeDirFlag `default:"." short:"C" help:"Run as if treefmt was started in the specified working directory instead of the current working directory"`
+	ClearCache            bool               `short:"c" help:"Reset the evaluation cache. Use in case the cache is not precise enough"`
+	ConfigFile            string             `type:"existingfile" default:"./treefmt.toml"`
+	FailOnChange          bool               `help:"Exit with error if any changes were made. Useful for CI"`
+	Formatters            []string           `help:"Specify formatters to apply. Defaults to all formatters"`
+	TreeRoot              string             `type:"existingdir" default:"."`
+	Verbosity             int                `name:"verbose" short:"v" type:"counter" default:"0" env:"LOG_LEVEL" help:"Set the verbosity of logs e.g. -vv"`
 
 	Format Format `cmd:"" default:"."`
 }

internal/cli/format_test.go

@@ -179,6 +179,40 @@ func TestCache(t *testing.T) {
 	as.Contains(string(out), "0 files changed")
 }
 
+func TestChangeWorkingDirectory(t *testing.T) {
+	as := require.New(t)
+
+	// capture current cwd, so we can replace it after the test is finished
+	cwd, err := os.Getwd()
+	as.NoError(err)
+
+	t.Cleanup(func() {
+		// return to the previous working directory
+		as.NoError(os.Chdir(cwd))
+	})
+
+	tempDir := test.TempExamples(t)
+	configPath := tempDir + "/treefmt.toml"
+
+	// test without any excludes
+	config := format.Config{
+		Formatters: map[string]*format.Formatter{
+			"echo": {
+				Command:  "echo",
+				Includes: []string{"*"},
+			},
+		},
+	}
+
+	test.WriteConfig(t, configPath, config)
+
+	// by default, we look for ./treefmt.toml and use the cwd for the tree root
+	// this should fail if the working directory hasn't been changed first
+	out, err := cmd(t, "-C", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 29))
+}
+
 func TestFailOnChange(t *testing.T) {
 	as := require.New(t)