parser_example_test.go

package yag_test

import (
	"fmt"

	"github.com/zoido/yag-config"
)

func ExampleParser_Usage() {
	type config struct {
		RequiredOption  string
		CustomEnvOption string
		NoFlagOption    string
		NoEnvOption     string
	}

	y := yag.New(yag.WithEnvPrefix("MY_APP_"))
	cfg := &config{}

	y.String(&cfg.RequiredOption, "required_option", "sets required option", yag.Required())
	y.String(
		&cfg.CustomEnvOption,
		"custom_env_option",
		"sets custom env option",
		yag.FromEnv("MY_OPTION_TWO"),
	)
	y.String(&cfg.NoFlagOption, "no_flag_option", "sets np flag option", yag.NoFlag())
	y.String(&cfg.NoFlagOption, "no_env_option", "sets no env option", yag.NoEnv())

	fmt.Print(y.Usage())

	// Output:
	// 	-required_option ($MY_APP_REQUIRED_OPTION) [required]
	// 		sets required option
	// 	-custom_env_option ($MY_OPTION_TWO)
	// 		sets custom env option
	// 	$MY_APP_NO_FLAG_OPTION
	// 		sets np flag option
	// 	-no_env_option
	// 		sets no env option
}

func ExampleErrHelp() {
	var foo string

	y := yag.New()

	y.String(&foo, "foo", "sets Foo")

	err := y.Parse([]string{"--help"})
	if err == yag.ErrHelp {
		fmt.Printf("--help flag passed")
	}

	// Output: --help flag passed
}

func ExampleParser_Args() {
	var foo string

	y := yag.New()

	y.String(&foo, "foo", "sets Foo")
	err := y.Parse([]string{"--foo", "x", "arg1", "arg2", "arg3"})
	if err != nil {
		fmt.Printf("error: %s", err)
	}

	fmt.Printf("foo: %q, args: %v", foo, y.Args())

	// Output: foo: "x", args: [arg1 arg2 arg3]
}