feat: accept ls and rm for list and delete commands

Every list command also answers to ls and every delete command to rm,
as in gh. flagAliases lets a command accept old flag names for renamed
flags without listing them in help, so singular gh names such as
--add-label can become primary while the plural names keep working.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/app_test.go

@@ -192,3 +192,39 @@ func TestRawJSONCommandsKeepJQToThemselves(t *testing.T) {
 	root.SetArgs([]string{"raw", "--json"})
 	require.ErrorContains(t, root.Execute(), "raw prints text; --json is not supported")
 }
+
+func TestVerbAndFlagAliases(t *testing.T) {
+	deps, _, _ := testDeps(t)
+	root := NewRoot(deps)
+	for _, args := range [][]string{{"issue", "ls"}, {"label", "rm"}, {"pr", "review", "ls"}} {
+		cmd, _, err := root.Find(args)
+		require.NoError(t, err)
+		require.Equal(t, map[string]string{"ls": "list", "rm": "delete"}[args[len(args)-1]], cmd.Name(), args)
+	}
+	// Aliases never shadow a sibling command.
+	walkCommands(root, func(cmd *cobra.Command) {
+		names := map[string]string{}
+		for _, child := range cmd.Commands() {
+			for _, name := range append([]string{child.Name()}, child.Aliases...) {
+				require.Empty(t, names[name], "%s %s is both %s and %s", cmd.CommandPath(), name, names[name], child.Name())
+				names[name] = child.Name()
+			}
+		}
+	})
+	var labels []string
+	edit := &cobra.Command{Use: "edit", RunE: func(*cobra.Command, []string) error { return nil }}
+	edit.Flags().StringSliceVar(&labels, "add-label", nil, "Add labels")
+	flagAliases(edit, map[string]string{"add-labels": "add-label"})
+	edit.SetArgs([]string{"--add-labels", "bug", "--add-label", "docs"})
+	require.NoError(t, edit.Execute())
+	require.Equal(t, []string{"bug", "docs"}, labels)
+	require.NotContains(t, edit.UsageString(), "add-labels")
+}
+
+// walkCommands calls visit for cmd and each of its descendants.
+func walkCommands(cmd *cobra.Command, visit func(*cobra.Command)) {
+	visit(cmd)
+	for _, child := range cmd.Commands() {
+		walkCommands(child, visit)
+	}
+}