Wrapping multiple errors in go

multiwrap_test.go

package playground

import (
	"errors"
	"fmt"
	"testing"

	"github.com/stretchr/testify/assert"
)

var (
	ErrOne   = errors.New("error one")
	ErrTwo   = errors.New("error two")
	ErrThree = errors.New("error three")
)

func TestErrMultiWrap(t *testing.T) {
	wrapper := fmt.Errorf("%w %w", ErrOne, ErrTwo)
	assert.ErrorIs(t, wrapper, ErrOne)
	assert.ErrorIs(t, wrapper, ErrTwo)
	assert.NotErrorIs(t, wrapper, ErrThree)

	{
		withThree := fmt.Errorf("%w %w", wrapper, ErrThree)
		assert.ErrorIs(t, withThree, ErrOne)
		assert.ErrorIs(t, withThree, ErrTwo)
		assert.ErrorIs(t, withThree, ErrThree)
	}

	{ // Let's make sure that shenanigans don't break it.
		withDuplicate := fmt.Errorf("%w %w", wrapper, ErrOne)
		assert.ErrorIs(t, withDuplicate, ErrOne)
		assert.ErrorIs(t, withDuplicate, ErrTwo)
		assert.NotErrorIs(t, withDuplicate, ErrThree)
	}
}