Quickcheck of sorting idempotency in Go (golang)

qc_test.go

package main

import (
    "reflect"
    "sort"
    "testing"
    "testing/quick"
)

type IntSlice []int

func (p IntSlice) Len() int            { return len(p) }
func (p IntSlice) Less(i, j int) bool  { return p[i] < p[j] }
func (p IntSlice) Swap(i, j int)       { p[i], p[j] = p[j], p[i] }

func TestSortIsIdempotent(t *testing.T) {
    prop := func(nums IntSlice) bool {
        sort.Sort(nums)
        nums2 := IntSlice(make([]int, len(nums)))
        copy(nums2, nums)
        sort.Sort(nums2)
        return reflect.DeepEqual(nums, nums2)
    }
    if err := quick.Check(prop, nil); err != nil {
        t.Error(err)
    }
}