issue #2329: return error when not running interactively

pkg/cmd/pr/checkout/checkout.go

@@ -111,6 +111,10 @@ func checkoutRun(opts *CheckoutOptions) error {
 		}
 
 	default:
+		if !opts.IO.CanPrompt() {
+			return cmdutil.FlagErrorf("must provide a pull request number (or URL or branch) when not running interactively")
+		}
+
 		httpClient, err := opts.HttpClient()
 		if err != nil {
 			return err

pkg/cmd/pr/checkout/checkout_test.go

@@ -64,8 +64,10 @@ func stubPR(repo, prHead string) (ghrepo.Interface, *api.PullRequest) {
 
 func Test_checkoutRun(t *testing.T) {
 	tests := []struct {
-		name        string
-		opts        *CheckoutOptions
+		name string
+		opts *CheckoutOptions
+		tty  bool
+
 		httpStubs   func(*httpmock.Registry)
 		runStubs    func(*run.CommandStubber)
 		promptStubs func(*prompter.MockPrompter)
@@ -191,7 +193,15 @@ func Test_checkoutRun(t *testing.T) {
 			},
 		},
 		{
-			name: "with no selected PR args, prompts for choice",
+			name: "with no selected PR args and not stdin tty, return error",
+			opts: &CheckoutOptions{
+				SelectorArg: "",
+			},
+			tty:     false,
+			wantErr: true,
+		},
+		{
+			name: "with no selected PR args and stdin tty, prompts for choice",
 			opts: &CheckoutOptions{
 				SelectorArg: "",
 				Finder: func() shared.PRFinder {
@@ -206,6 +216,7 @@ func Test_checkoutRun(t *testing.T) {
 					return config.NewBlankConfig(), nil
 				},
 			},
+			tty: true,
 			httpStubs: func(reg *httpmock.Registry) {
 				reg.Register(httpmock.GraphQL(`query PullRequestList\b`), httpmock.FileResponse("./fixtures/prList.json"))
 			},
@@ -232,6 +243,12 @@ func Test_checkoutRun(t *testing.T) {
 			opts := tt.opts
 
 			ios, _, stdout, stderr := iostreams.Test()
+			if tt.tty {
+				ios.SetStdinTTY(tt.tty)
+				ios.SetStdoutTTY(tt.tty)
+				ios.SetStderrTTY(tt.tty)
+			}
+
 			opts.IO = ios
 			httpReg := &httpmock.Registry{}
 			defer httpReg.Verify(t)