WIP add --checkout option

pkg/cmd/issue/develop/develop.go

@@ -6,8 +6,11 @@ import (
 
 	"github.com/MakeNowJust/heredoc"
 	"github.com/cli/cli/v2/api"
+	"github.com/cli/cli/v2/context"
+	"github.com/cli/cli/v2/git"
 	"github.com/cli/cli/v2/internal/config"
 	"github.com/cli/cli/v2/internal/ghrepo"
+	"github.com/cli/cli/v2/internal/run"
 	"github.com/cli/cli/v2/pkg/cmd/issue/shared"
 	"github.com/cli/cli/v2/pkg/cmdutil"
 	"github.com/cli/cli/v2/pkg/iostreams"
@@ -19,6 +22,7 @@ type DevelopOptions struct {
 	Config     func() (config.Config, error)
 	IO         *iostreams.IOStreams
 	BaseRepo   func() (ghrepo.Interface, error)
+	Remotes    func() (context.Remotes, error)
 
 	IssueRepo     string
 	IssueSelector string
@@ -33,15 +37,17 @@ func NewCmdDevelop(f *cmdutil.Factory, runF func(*DevelopOptions) error) *cobra.
 		HttpClient: f.HttpClient,
 		Config:     f.Config,
 		BaseRepo:   f.BaseRepo,
+		Remotes:    f.Remotes,
 	}
 
 	cmd := &cobra.Command{
-		Use:   "develop",
-		Short: "Manage branches for an issue",
+		Use:   "develop [flags] {<number> | <url>}",
+		Short: "Manage linked branches for an issue",
 		Example: heredoc.Doc(`
 			$ gh issue develop --list 123 # list branches for issue 123
 			$ gh issue develop --issue-repo "github/cli" 123 list branches for issue 123 in repo "github/cli"
 			$ gh issue develop 123 --name "my-branch" --head main
+			$ gh issue develop 123 --checkout # checkout the branch for issue 123 after creating it
 			`),
 		Args: cmdutil.ExactArgs(1, "issue number is required"),
 		RunE: func(cmd *cobra.Command, args []string) error {
@@ -53,9 +59,10 @@ func NewCmdDevelop(f *cmdutil.Factory, runF func(*DevelopOptions) error) *cobra.
 		},
 	}
 	fl := cmd.Flags()
-	fl.StringVarP(&opts.Name, "name", "n", "", "Name of the branch to create")
 	fl.StringVarP(&opts.BaseBranch, "base-branch", "b", "", "Name of the base branch")
-	fl.StringVarP(&opts.IssueRepo, "issue-repo", "i", "", "Name of the issue's repository")
+	fl.BoolVarP(&opts.Checkout, "checkout", "c", false, "Checkout the branch after creating it")
+	fl.StringVarP(&opts.IssueRepo, "issue-repo", "i", "", "Name or URL of the issue's repository")
+	fl.StringVarP(&opts.Name, "name", "n", "", "Name of the branch to create")
 	return cmd
 }
 
@@ -69,6 +76,7 @@ func developRun(opts *DevelopOptions) (err error) {
 	if err != nil {
 		return err
 	}
+	opts.IO.StartProgressIndicator()
 	repo, err := api.GitHubRepo(apiClient, baseRepo)
 	if err != nil {
 		return err
@@ -98,11 +106,57 @@ func developRun(opts *DevelopOptions) (err error) {
 	}
 
 	ref, err := api.CreateBranchIssueReference(apiClient, repo, params)
+	opts.IO.StopProgressIndicator()
 	if ref != nil {
 		fmt.Fprintf(opts.IO.Out, "Created %s\n", ref.BranchName)
+
+		if opts.Checkout {
+			return checkoutBranch(opts, baseRepo, ref.BranchName)
+		}
 	}
 	if err != nil {
 		return err
 	}
 	return
 }
+
+func checkoutBranch(opts *DevelopOptions, baseRepo ghrepo.Interface, checkoutBranch string) (err error) {
+
+	remotes, err := opts.Remotes()
+	if err != nil {
+		return err
+	}
+
+	baseRemote, err := remotes.FindByRepo(baseRepo.RepoOwner(), baseRepo.RepoName())
+	if err != nil {
+		return err
+	}
+
+	if git.HasLocalBranch(checkoutBranch) {
+		if err := git.CheckoutBranch(checkoutBranch); err != nil {
+			return err
+		}
+	} else {
+		gitFetch, err := git.GitCommand("fetch", "origin", fmt.Sprintf("+refs/heads/%[1]s:refs/remotes/origin/%[1]s", checkoutBranch))
+
+		if err != nil {
+			return err
+		}
+
+		gitFetch.Stdout = opts.IO.Out
+		gitFetch.Stderr = opts.IO.ErrOut
+		err = run.PrepareCmd(gitFetch).Run()
+		if err != nil {
+			return err
+		}
+		if err := git.CheckoutNewBranch(baseRemote.Name, checkoutBranch); err != nil {
+			return err
+		}
+	}
+
+	if err := git.Pull(baseRemote.Name, checkoutBranch); err != nil {
+		_, _ = fmt.Fprintf(opts.IO.ErrOut, "%s warning: not possible to fast-forward to: %q\n", opts.IO.ColorScheme().WarningIcon(), checkoutBranch)
+	}
+
+	return nil
+}