chore: make execCmdInDir public

main.go

@@ -1,11 +1,9 @@
 package main
 
 import (
-	"bytes"
 	_ "embed"
 	"fmt"
 	"os"
-	"os/exec"
 	"path/filepath"
 
 	"go.einride.tech/mage-tools/mglog"
@@ -94,14 +92,13 @@ func initMageTools() {
 			panic(err)
 		}
 	}
-
-	if err := execCommandInDirectory(mageDir, "go", []string{"mod", "init", "mage-tools"}...); err != nil {
+	if err := mgtool.RunInDir("go", mageDir, []string{"mod", "init", "mage-tools"}...); err != nil {
 		panic(err)
 	}
 	if err != nil {
 		panic(err)
 	}
-	if err := execCommandInDirectory(mageDir, "go", []string{"mod", "tidy"}...); err != nil {
+	if err := mgtool.RunInDir("go", mageDir, []string{"mod", "tidy"}...); err != nil {
 		panic(err)
 	}
 	gitIgnore, err := os.OpenFile(".gitignore", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
@@ -115,14 +112,3 @@ func initMageTools() {
 	// TODO: Output some documentation, next steps after init, and useful links.
 	logger.Info("mage-tools initialized!")
 }
-
-func execCommandInDirectory(dir string, command string, args ...string) (err error) {
-	c := exec.Command(command, args...)
-	c.Env = os.Environ()
-	c.Stderr = &bytes.Buffer{}
-	c.Stdout = &bytes.Buffer{}
-	c.Stdin = os.Stdin
-	c.Dir = dir
-
-	return c.Run()
-}

mgtool/exec.go

@@ -0,0 +1,39 @@
+package mgtool
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"os/exec"
+)
+
+// RunInDir runs the given command in the specified directory, discarding stdout.
+func RunInDir(cmd, dir string, args ...string) error {
+	b := io.Discard
+	return run(cmd, dir, b, os.Stderr, args...)
+}
+
+// RunInDirV runs the given command in the specified directory, outputting to stdout.
+func RunInDirV(cmd, dir string, args ...string) error {
+	return run(cmd, dir, os.Stdout, os.Stderr, args...)
+}
+
+// OutputRunInDir run the given command in the specified directory, returning the output ad a string.
+func OutputRunInDir(cmd, dir string, args ...string) (string, error) {
+	b := &bytes.Buffer{}
+	if err := run(cmd, dir, b, os.Stderr, args...); err != nil {
+		return "", err
+	}
+	return b.String(), nil
+}
+
+func run(cmd, dir string, stdout, stderr io.Writer, args ...string) error {
+	c := exec.Command(cmd, args...)
+	c.Env = os.Environ()
+	c.Stderr = stdout
+	c.Stdout = stderr
+	c.Stdin = os.Stdin
+	c.Dir = dir
+
+	return c.Run()
+}