More enum fixes.

README.md

@@ -4,40 +4,42 @@
 # Kong is a command-line parser for Go
 [![](https://godoc.org/github.com/alecthomas/kong?status.svg)](http://godoc.org/github.com/alecthomas/kong) [![CircleCI](https://img.shields.io/circleci/project/github/alecthomas/kong.svg)](https://circleci.com/gh/alecthomas/kong) [![Go Report Card](https://goreportcard.com/badge/github.com/alecthomas/kong)](https://goreportcard.com/report/github.com/alecthomas/kong) [![Slack chat](https://img.shields.io/static/v1?logo=slack&style=flat&label=slack&color=green&message=gophers)](https://gophers.slack.com/messages/CN9DS8YF3)
 
-<!-- TOC depthfrom:2 updateonsave:true withlinks:true -->
+<!-- https://github.com/naokazuterada/MarkdownTOC -->
 
-- [Introduction](#introduction)
+<!-- MarkdownTOC autolink="true" style="ordered" indent="    " -->
-- [Help](#help)
-    - [Help as a user of a Kong application](#help-as-a-user-of-a-kong-application)
-    - [Defining help in Kong](#defining-help-in-kong)
-- [Command handling](#command-handling)
-    - [Switch on the command string](#switch-on-the-command-string)
-    - [Attach a Run... error method to each command](#attach-a-run-error-method-to-each-command)
-- [Hooks: BeforeResolve, BeforeApply, AfterApply and the Bind option](#hooks-beforeresolve-beforeapply-afterapply-and-the-bind-option)
-- [Flags](#flags)
-- [Commands and sub-commands](#commands-and-sub-commands)
-- [Branching positional arguments](#branching-positional-arguments)
-- [Terminating positional arguments](#terminating-positional-arguments)
-- [Slices](#slices)
-- [Maps](#maps)
-- [Custom named decoders](#custom-named-decoders)
-- [Supported field types](#supported-field-types)
-- [Custom decoders mappers](#custom-decoders-mappers)
-- [Supported tags](#supported-tags)
-- [Plugins](#plugins)
-- [Dynamic Commands](#dynamic-commands)
-- [Variable interpolation](#variable-interpolation)
-- [Validation](#validation)
-- [Modifying Kong's behaviour](#modifying-kongs-behaviour)
-    - [Namehelp and Descriptionhelp - set the application name description](#namehelp-and-descriptionhelp---set-the-application-name-description)
-    - [Configurationloader, paths... - load defaults from configuration files](#configurationloader-paths---load-defaults-from-configuration-files)
-    - [Resolver... - support for default values from external sources](#resolver---support-for-default-values-from-external-sources)
-    - [*Mapper... - customising how the command-line is mapped to Go values](#mapper---customising-how-the-command-line-is-mapped-to-go-values)
-    - [ConfigureHelpHelpOptions and HelpHelpFunc - customising help](#configurehelphelpoptions-and-helphelpfunc---customising-help)
-    - [Bind... - bind values for callback hooks and Run methods](#bind---bind-values-for-callback-hooks-and-run-methods)
-    - [Other options](#other-options)
 
-<!-- /TOC -->
+1. [Introduction](#introduction)
+1. [Help](#help)
+    1. [Help as a user of a Kong application](#help-as-a-user-of-a-kong-application)
+    1. [Defining help in Kong](#defining-help-in-kong)
+1. [Command handling](#command-handling)
+    1. [Switch on the command string](#switch-on-the-command-string)
+    1. [Attach a `Run(...) error` method to each command](#attach-a-run-error-method-to-each-command)
+1. [Hooks: BeforeResolve\(\), BeforeApply\(\), AfterApply\(\) and the Bind\(\) option](#hooks-beforeresolve-beforeapply-afterapply-and-the-bind-option)
+1. [Flags](#flags)
+1. [Commands and sub-commands](#commands-and-sub-commands)
+1. [Branching positional arguments](#branching-positional-arguments)
+1. [Positional arguments](#positional-arguments)
+1. [Slices](#slices)
+1. [Maps](#maps)
+1. [Custom named decoders](#custom-named-decoders)
+1. [Supported field types](#supported-field-types)
+1. [Custom decoders \(mappers\)](#custom-decoders-mappers)
+1. [Supported tags](#supported-tags)
+1. [Plugins](#plugins)
+1. [Dynamic Commands](#dynamic-commands)
+1. [Variable interpolation](#variable-interpolation)
+1. [Validation](#validation)
+1. [Modifying Kong's behaviour](#modifying-kongs-behaviour)
+    1. [`Name(help)` and `Description(help)` - set the application name description](#namehelp-and-descriptionhelp---set-the-application-name-description)
+    1. [`Configuration(loader, paths...)` - load defaults from configuration files](#configurationloader-paths---load-defaults-from-configuration-files)
+    1. [`Resolver(...)` - support for default values from external sources](#resolver---support-for-default-values-from-external-sources)
+    1. [`*Mapper(...)` - customising how the command-line is mapped to Go values](#mapper---customising-how-the-command-line-is-mapped-to-go-values)
+    1. [`ConfigureHelp(HelpOptions)` and `Help(HelpFunc)` - customising help](#configurehelphelpoptions-and-helphelpfunc---customising-help)
+    1. [`Bind(...)` - bind values for callback hooks and Run\(\) methods](#bind---bind-values-for-callback-hooks-and-run-methods)
+    1. [Other options](#other-options)
+
+<!-- /MarkdownTOC -->
 
 ## Introduction
 
@@ -333,11 +335,14 @@ var CLI struct {
 
 This looks a little verbose in this contrived example, but typically this will not be the case.
 
-## Terminating positional arguments
+## Positional arguments
 
-If a [mapped type](#mapper---customising-how-the-command-line-is-mapped-to-go-values) is tagged with `arg` it will be treated as the final positional values to be parsed on the command line.
+If a field is tagged with `arg:""` it will be treated as the final positional
+value to be parsed on the command line. By default positional arguments are
+required, but specifying `optional:""` will alter this.
 
-If a positional argument is a slice, all remaining arguments will be appended to that slice.
+If a positional argument is a slice, all remaining arguments will be appended
+to that slice.
 
 ## Slices
 
@@ -429,7 +434,7 @@ Both can coexist with standard Tag parsing.
 Tag                    | Description
 -----------------------| -------------------------------------------
 `cmd:""`               | If present, struct is a command.
-`arg:""`               | If present, field is an argument.
+`arg:""`               | If present, field is an argument. Required by default.
 `env:"X"`              | Specify envar to use for default value.
 `name:"X"`             | Long name, for overriding field name.
 `help:"X"`             | Help text.

go.mod

@@ -1,6 +1,7 @@
 module github.com/alecthomas/kong
 
 require (
+	github.com/alecthomas/repr v0.0.0-20210801044451-80ca428c5142
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pkg/errors v0.9.1
 	github.com/stretchr/testify v1.7.0

go.sum

@@ -1,3 +1,5 @@
+github.com/alecthomas/repr v0.0.0-20210801044451-80ca428c5142 h1:8Uy0oSf5co/NZXje7U1z8Mpep++QJOldL2hs/sBQf48=
+github.com/alecthomas/repr v0.0.0-20210801044451-80ca428c5142/go.mod h1:2kn6fqh/zIyPLmm3ugklbEi5hg5wS435eygvNfaDQL8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=

kong_test.go

@@ -10,6 +10,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/alecthomas/kong"
+	"github.com/alecthomas/repr"
 )
 
 func mustNew(t *testing.T, cli interface{}, options ...kong.Option) *kong.Kong {
@@ -1384,17 +1385,63 @@ func TestOptionReturnsErr(t *testing.T) {
 }
 
 func TestEnumValidation(t *testing.T) {
-	var cli struct {
+	tests := []struct {
-		Enum string `arg:"" enum:"one,two"`
+		name string
+		cli  interface{}
+		fail bool
+	}{
+		{
+			"Arg",
+			&struct {
+				Enum string `arg:"" enum:"one,two"`
+			}{},
+			false,
+		},
+		{
+			"RequiredArg",
+			&struct {
+				Enum string `required:"" arg:"" enum:"one,two"`
+			}{},
+			false,
+		},
+		{
+			"OptionalArg",
+			&struct {
+				Enum string `optional:"" arg:"" enum:"one,two"`
+			}{},
+			true,
+		},
+		{
+			"RepeatedArgs",
+			&struct {
+				Enum []string `arg:"" enum:"one,two"`
+			}{},
+			false,
+		},
+		{
+			"RequiredRepeatedArgs",
+			&struct {
+				Enum []string `required:"" arg:"" enum:"one,two"`
+			}{},
+			false,
+		},
+		{
+			"OptionalRepeatedArgs",
+			&struct {
+				Enum []string `optional:"" arg:"" enum:"one,two"`
+			}{},
+			false,
+		},
 	}
-	_, err := kong.New(&cli)
+	for _, test := range tests {
-	require.Error(t, err)
+		test := test
-}
+		t.Run(test.name, func(t *testing.T) {
-
+			_, err := kong.New(test.cli)
-func TestEnumValidationSlice(t *testing.T) {
+			if test.fail {
-	var cli struct {
+				require.Error(t, err, repr.String(test.cli))
-		Enum []string `arg:"" enum:"one,two"`
+			} else {
+				require.NoError(t, err, repr.String(test.cli))
+			}
+		})
 	}
-	_, err := kong.New(&cli)
-	require.NoError(t, err)
 }

tag.go

@@ -186,6 +186,8 @@ func hydrateTag(t *Tag, typ reflect.Type) error { // nolint: gocyclo
 	// Arguments with defaults are always optional.
 	if t.Arg && t.Default != "" {
 		t.Optional = true
+	} else if t.Arg && !optional { // Arguments are required unless explicitly made optional.
+		t.Required = true
 	}
 	t.Name = t.Get("name")
 	t.Help = t.Get("help")