Add --base to agentpr pr edit to retarget a PR

cmd/agentpr/main.go

@@ -5,7 +5,7 @@
 //
 //	agentpr pr create --repo owner/repo --base main --head feature --title T --body B
 //	agentpr pr comment --repo owner/repo --pr 12 --body "..."
-//	agentpr pr edit --repo owner/repo --pr 12 --title T --body B
+//	agentpr pr edit --repo owner/repo --pr 12 --title T --body B --base B
 //	agentpr issue create --repo owner/repo --title T --body B
 //	agentpr issue comment --repo owner/repo --issue 12 --body "..."
 //	agentpr issue edit --repo owner/repo --issue 12 --title T --body B
@@ -169,11 +169,11 @@ func newCommentCmd(numFlag, noun, short string) *cobra.Command {
 }
 
 func newPREditCmd() *cobra.Command {
-	var repo, title, body string
+	var repo, title, body, base string
 	var pr int
 	cmd := &cobra.Command{
 		Use:          "edit",
-		Short:        "Edit a pull request's title and/or body",
+		Short:        "Edit a pull request's title, body and/or base branch",
 		SilenceUsage: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			owner, name, err := agent.ParseRepo(repo)
@@ -187,6 +187,12 @@ func newPREditCmd() *cobra.Command {
 			if err != nil {
 				return err
 			}
+			if cmd.Flags().Changed("base") {
+				if base == "" {
+					return fmt.Errorf("--base cannot be empty")
+				}
+				opts.Base = &base
+			}
 			c, err := client()
 			if err != nil {
 				return err
@@ -204,6 +210,7 @@ func newPREditCmd() *cobra.Command {
 	f.IntVar(&pr, "pr", 0, "PR number (required)")
 	f.StringVar(&title, "title", "", "New PR title (unchanged when omitted)")
 	f.StringVar(&body, "body", "", "New PR body (unchanged when omitted)")
+	f.StringVar(&base, "base", "", "New base branch (unchanged when omitted)")
 	_ = cmd.MarkFlagRequired("repo")
 	_ = cmd.MarkFlagRequired("pr")
 	return cmd
@@ -225,7 +232,10 @@ func editOptions(cmd *cobra.Command, title, body string) (agent.EditOptions, err
 	if cmd.Flags().Changed("body") {
 		opts.Body = &body
 	}
-	if opts.Title == nil && opts.Body == nil {
+	if opts.Title == nil && opts.Body == nil && !cmd.Flags().Changed("base") {
+		if cmd.Flags().Lookup("base") != nil {
+			return opts, fmt.Errorf("at least one of --title, --body or --base is required")
+		}
 		return opts, fmt.Errorf("at least one of --title or --body is required")
 	}
 	return opts, nil

cmd/agentpr/main_test.go

@@ -20,7 +20,7 @@ func TestExecuteBadRepoErrors(t *testing.T) {
 	}
 }
 
-// `pr edit` with neither --title nor --body has nothing to send; it must fail
+// `pr edit` with none of --title, --body or --base has nothing to send; it must fail
 // with a usage error before any Vault/Gitea call, so this stays hermetic.
 func TestPREditRequiresTitleOrBody(t *testing.T) {
 	cmd := newRootCmd()
@@ -29,13 +29,32 @@ func TestPREditRequiresTitleOrBody(t *testing.T) {
 	cmd.SetErr(io.Discard)
 	err := cmd.Execute()
 	if err == nil {
-		t.Fatal("Execute() = nil, want an error when neither --title nor --body is given")
+		t.Fatal("Execute() = nil, want an error when no edit flag is given")
 	}
-	if !strings.Contains(err.Error(), "--title or --body") {
+	if !strings.Contains(err.Error(), "--title, --body or --base") {
 		t.Errorf("error = %q, want it to name the missing flags", err)
 	}
 }
 
+// An empty --base names no branch to retarget to; it must fail before any
+// Vault/Gitea call rather than be sent.
+func TestPREditRejectsEmptyBase(t *testing.T) {
+	err := execute("pr", "edit", "--repo", "unkin/repo", "--pr", "7", "--base", "")
+	if err == nil {
+		t.Fatal("Execute() = nil, want an error for an empty --base")
+	}
+	if !strings.Contains(err.Error(), "--base cannot be empty") {
+		t.Errorf("error = %q, want it to reject the empty base", err)
+	}
+}
+
+// issue edit has no --base, so its usage error must not suggest one.
+func TestIssueEditHasNoBaseFlag(t *testing.T) {
+	if err := execute("issue", "edit", "--repo", "unkin/repo", "--issue", "12", "--base", "x"); err == nil {
+		t.Fatal("Execute() = nil, want an unknown-flag error for issue edit --base")
+	}
+}
+
 // Gitea silently ignores an empty title, so `pr edit --title ""` would report
 // success while changing nothing; it must fail before any Vault/Gitea call.
 func TestPREditRejectsEmptyTitle(t *testing.T) {