go-cmp reflect.DeepEqual Slice Failure

单测是遇到对比两个slice时, 因为元素是无序的, 导致相等的item, 判断失败
代码如下:

package main

import (
    "fmt"
    "github.com/google/go-cmp/cmp"
)
type Item struct {
    Media string
    Size  int64
}
func main() {
    standard := []Item{
        Item{
            Media: "SSD",
            Size:  100,
        },
        Item{
            Media: "HDD",
            Size:  200,
        },
    }
    test1 := []Item{
        Item{
            Media: "HDD",
            Size:  200,
        },
        Item{
            Media: "SSD",
            Size:  100,
        },
    }
    fmt.Println(cmp.Equal(standard, test1)) // false 
}

期望是: true, 但是实际: false

cmp的Equal方法提供了 opts自定义函数

trans := cmp.Transformer(
        "Sort",
        func(in []Item) []Item {
            sort.Slice(
                in, 
                func(i, j int) bool {
                    return in[i].Size < in[j].Size
                })  
            return in
        }) 

fmt.Println(cmp.Equal(standard, test1,trans)) // true