package validate

import (
	"errors"
	"fmt"
	"testing"
)

func ExampleRequired() {
	notBlank := Required[string]()
	fmt.Println(notBlank(""))
	// Output: is required
}

func TestRequired(t *testing.T) {
	t.Run("string", func(t *testing.T) {
		v := Required[string]()
		if err := v(""); !errors.Is(err, ErrRequired) {
			t.Error("empty string should be required, got", err)
		}
		if err := v("x"); err != nil {
			t.Error("non-empty string should pass, got", err)
		}
	})

	t.Run("int", func(t *testing.T) {
		v := Required[int]()
		if err := v(0); !errors.Is(err, ErrRequired) {
			t.Error("zero should be required, got", err)
		}
		if err := v(1); err != nil {
			t.Error("non-zero should pass, got", err)
		}
	})

	t.Run("pointer", func(t *testing.T) {
		v := Required[*int]()
		if err := v(nil); !errors.Is(err, ErrRequired) {
			t.Error("nil pointer should be required, got", err)
		}
		n := 0
		if err := v(&n); err != nil {
			t.Error("non-nil pointer should pass, got", err)
		}
	})
}