package ut

import (
	"errors"
	"testing"

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

func TestErrCombineNil(t *testing.T) {
	assert.Nil(t, ErrCombine(nil))
}

func TestErrCombineEmpty(t *testing.T) {
	assert.Nil(t, ErrCombine())
}

func TestErrCombineErrIsKept(t *testing.T) {
	var err = errors.New("err")

	assert.Equal(t, err, ErrCombine(err))
}

func TestErrCombineErrIsAssigned(t *testing.T) {
	var err = errors.New("err")

	assert.Equal(t, err, ErrCombine(nil, err))
}

func TestErrCombineAggregates(t *testing.T) {
	var err1 = errors.New("err1")
	var err2 = errors.New("err2")

	var err = ErrCombine(err1, err2)

	assert.NotNil(t, err)
	require.Implements(t, (*Errors)(nil), err)
	var errs = err.(Errors).Errs()
	assert.Equal(t, 2, len(errs))
	assert.Equal(t, err1, errs[0])
	assert.Equal(t, err2, errs[1])
}

func TestErrCombineErrorContainsBothMessages(t *testing.T) {
	var err1 = errors.New("err1")
	var err2 = errors.New("err2")

	var err = ErrCombine(err1, err2).Error()

	assert.Contains(t, err, err1.Error())
	assert.Contains(t, err, err2.Error())
}

func TestErrCombineExpandsFirstArgument(t *testing.T) {
	var err1 = errors.New("err1")
	var err2 = errors.New("err2")
	var err3 = errors.New("err3")

	var err = ErrCombine(ErrCombine(err1, err2), err3)

	assert.NotNil(t, err)
	require.Implements(t, (*Errors)(nil), err)
	var errs = err.(Errors).Errs()
	assert.Equal(t, 3, len(errs))
	assert.Equal(t, err1, errs[0])
	assert.Equal(t, err2, errs[1])
	assert.Equal(t, err3, errs[2])
}

func TestErrCombineDoesNotExpandConsecutiveArguments(t *testing.T) {
	var err1 = errors.New("err1")
	var err2 = errors.New("err2")
	var err3 = errors.New("err3")

	var err = ErrCombine(err1, ErrCombine(err2, err3))

	assert.NotNil(t, err)
	require.Implements(t, (*Errors)(nil), err)
	var errs = err.(Errors).Errs()
	assert.Equal(t, 2, len(errs))
	assert.Equal(t, err1, errs[0])
	assert.Implements(t, (*Errors)(nil), errs[1])
}