feat: add gh.ExecInteractive (#115)

- add gh.ExecInteractive
- add gh.ExecContext
- add support for GH_PATH environment variable

Co-authored-by: Mislav Marohnić <git@mislav.net>

gh.go

@@ -7,8 +7,10 @@ package gh
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 	"os"
 	"os/exec"
@@ -24,33 +26,55 @@ import (
 	"github.com/cli/safeexec"
 )
 
-// Exec gh command with provided arguments.
-func Exec(args ...string) (stdOut, stdErr bytes.Buffer, err error) {
-	path, err := path()
+// Exec invokes a gh command in a subprocess and captures the output and error streams.
+func Exec(args ...string) (stdout, stderr bytes.Buffer, err error) {
+	ghExe, err := ghLookPath()
 	if err != nil {
-		err = fmt.Errorf("could not find gh executable in PATH. error: %w", err)
 		return
 	}
-	return run(path, nil, args...)
+	err = run(context.Background(), ghExe, nil, nil, &stdout, &stderr, args)
+	return
+}
+
+// ExecContext invokes a gh command in a subprocess and captures the output and error streams.
+func ExecContext(ctx context.Context, args ...string) (stdout, stderr bytes.Buffer, err error) {
+	ghExe, err := ghLookPath()
+	if err != nil {
+		return
+	}
+	err = run(ctx, ghExe, nil, nil, &stdout, &stderr, args)
+	return
+}
+
+// Exec invokes a gh command in a subprocess with its stdin, stdout, and stderr streams connected to
+// those of the parent process. This is suitable for running gh commands with interactive prompts.
+func ExecInteractive(ctx context.Context, args ...string) error {
+	ghExe, err := ghLookPath()
+	if err != nil {
+		return err
+	}
+	return run(ctx, ghExe, nil, os.Stdin, os.Stdout, os.Stderr, args)
 }
 
-func path() (string, error) {
+func ghLookPath() (string, error) {
+	if ghExe := os.Getenv("GH_PATH"); ghExe != "" {
+		return ghExe, nil
+	}
 	return safeexec.LookPath("gh")
 }
 
-func run(path string, env []string, args ...string) (stdOut, stdErr bytes.Buffer, err error) {
-	cmd := exec.Command(path, args...)
-	cmd.Stdout = &stdOut
-	cmd.Stderr = &stdErr
+func run(ctx context.Context, ghExe string, env []string, stdin io.Reader, stdout, stderr io.Writer, args []string) error {
+	cmd := exec.CommandContext(ctx, ghExe, args...)
+	cmd.Stdin = stdin
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
 	if env != nil {
 		cmd.Env = env
 	}
-	err = cmd.Run()
-	if err != nil {
-		err = fmt.Errorf("failed to run gh: %s. error: %w", stdErr.String(), err)
-		return
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("gh execution failed: %w", err)
 	}
-	return
+	return nil
 }
 
 // RESTClient builds a client to send requests to GitHub REST API endpoints.

gh_test.go

@@ -1,11 +1,14 @@
 package gh
 
 import (
+	"bytes"
+	"context"
 	"fmt"
 	"net/http"
 	"os"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/cli/go-gh/pkg/api"
 	"github.com/cli/go-gh/pkg/config"
@@ -30,22 +33,43 @@ func TestHelperProcess(t *testing.T) {
 	os.Exit(0)
 }
 
+func TestHelperProcessLongRunning(t *testing.T) {
+	if os.Getenv("GH_WANT_HELPER_PROCESS") != "1" {
+		return
+	}
+	args := os.Args[3:]
+	fmt.Fprintf(os.Stdout, "%v", args)
+	fmt.Fprint(os.Stderr, "going to sleep...")
+	time.Sleep(10 * time.Second)
+	fmt.Fprint(os.Stderr, "...going to exit")
+	os.Exit(0)
+}
+
 func TestRun(t *testing.T) {
-	stdOut, stdErr, err := run(os.Args[0],
-		[]string{"GH_WANT_HELPER_PROCESS=1"},
-		"-test.run=TestHelperProcess", "--", "gh", "issue", "list")
+	var stdout, stderr bytes.Buffer
+	err := run(context.TODO(), os.Args[0], []string{"GH_WANT_HELPER_PROCESS=1"}, nil, &stdout, &stderr,
+		[]string{"-test.run=TestHelperProcess", "--", "gh", "issue", "list"})
 	assert.NoError(t, err)
-	assert.Equal(t, "[gh issue list]", stdOut.String())
-	assert.Equal(t, "", stdErr.String())
+	assert.Equal(t, "[gh issue list]", stdout.String())
+	assert.Equal(t, "", stderr.String())
 }
 
 func TestRunError(t *testing.T) {
-	stdOut, stdErr, err := run(os.Args[0],
-		[]string{"GH_WANT_HELPER_PROCESS=1"},
-		"-test.run=TestHelperProcess", "--", "gh", "issue", "list", "error")
-	assert.EqualError(t, err, "failed to run gh: process exited with error. error: exit status 1")
-	assert.Equal(t, "", stdOut.String())
-	assert.Equal(t, "process exited with error", stdErr.String())
+	var stdout, stderr bytes.Buffer
+	err := run(context.TODO(), os.Args[0], []string{"GH_WANT_HELPER_PROCESS=1"}, nil, &stdout, &stderr,
+		[]string{"-test.run=TestHelperProcess", "--", "gh", "error"})
+	assert.EqualError(t, err, "gh execution failed: exit status 1")
+	assert.Equal(t, "", stdout.String())
+	assert.Equal(t, "process exited with error", stderr.String())
+}
+
+func TestRunInteractiveContextCanceled(t *testing.T) {
+	// pass current time to ensure that deadline has already passed
+	ctx, cancel := context.WithDeadline(context.Background(), time.Now())
+	cancel()
+	err := run(ctx, os.Args[0], []string{"GH_WANT_HELPER_PROCESS=1"}, nil, nil, nil,
+		[]string{"-test.run=TestHelperProcessLongRunning", "--", "gh", "issue", "list"})
+	assert.EqualError(t, err, "gh execution failed: context deadline exceeded")
 }
 
 func TestRESTClient(t *testing.T) {

pkg/auth/auth.go

@@ -37,7 +37,12 @@ func TokenForHost(host string) (string, string) {
 		return token, source
 	}
 
-	if ghExe, err := safeexec.LookPath("gh"); err == nil {
+	ghExe := os.Getenv("GH_PATH")
+	if ghExe == "" {
+		ghExe, _ = safeexec.LookPath("gh")
+	}
+
+	if ghExe != "" {
 		if token, source := tokenFromGh(ghExe, host); token != "" {
 			return token, source
 		}