如何为 sort.Slice() 编写测试？

Question

鉴于如何sort.Slice(array, func(int, int) bool)在传入函数中使用数组，您将如何为匿名函数编写测试？来自go 文档sort.Slice()的示例代码是：package mainimport (    "fmt"    "sort")func main() {    people := []struct {        Name string        Age  int    }{        {"Gopher", 7},        {"Alice", 55},        {"Vera", 24},        {"Bob", 75},    }    sort.Slice(people, func(i, j int) bool { return people[i].Name < people[j].Name })    fmt.Println("By name:", people)    sort.Slice(people, func(i, j int) bool { return people[i].Age < people[j].Age })    fmt.Println("By age:", people)}如果将匿名函数分解为两个单独的函数（例如，comparePeopleByName(i, j int)和comparePeopleByAge(i, j, int)），您将如何测试它们？将函数绑定到闭包上似乎是个奇怪的想法。注意：我认为测试sort.Slice()自己是一种不好的形式；它随语言一起提供，不应该（需要？）进行测试。

Answer 1

package main

import (

    "fmt"

    "sort"

)

func main() {

    people := []struct {

        Name string

        Age  int

    }{

        {"Gopher", 7},

        {"Alice", 55},

        {"Vera", 24},

        {"Bob", 75},

    }

    sort.Slice(people, func(i, j int) bool { return people[i].Name < people[j].Name })

    fmt.Println("By name:", people)

    sort.Slice(people, func(i, j int) bool { return people[i].Age < people[j].Age })

    fmt.Println("By age:", people)

}

如果将匿名函数分解为两个单独的函数（例如，comparePeopleByName(i, j int)和comparePeopleByAge(i, j, int)），您将如何测试它们？

将函数绑定到闭包上似乎是个奇怪的想法。

注意：我认为测试sort.Slice()自己是一种不好的形式；它随语言一起提供，不应该（需要？）进行测试。

Answer 2

胡思乱想后，我写了这段代码。它使用工厂来创建方法，以便切片包含在函数的闭包中。

我把它放在一个要点中以便于玩弄：https ://gist.github.com/docwhat/e3b13265d24471651e02f7d7a42e7d2c

// main.go

package main

import (

    "fmt"

    "sort"

)

type Person struct {

    Name string

    Age  int

}

func comparePeopleByName(people []Person) func(int, int) bool {

    return func(i, j int) bool {

        return people[i].Name < people[j].Name

    }

}

func comparePeopleByAge(people []Person) func(int, int) bool {

    return func(i, j int) bool {

        return people[i].Age < people[j].Age

    }

}

func main() {

    people := []Person{

        {"Gopher", 7},

        {"Alice", 55},

        {"Vera", 24},

        {"Bob", 75},

    }

    sort.Slice(people, comparePeopleByName(people))

    fmt.Println("By name:", people)

    sort.Slice(people, comparePeopleByAge(people))

    fmt.Println("By age:", people)

}

// main_test.go

package main

import "testing"

func TestComparePeopleByName(t *testing.T) {

    testCases := []struct {

        desc     string

        a, b     Person

        expected bool

    }{

        {"a < b", Person{"bob", 1}, Person{"krabs", 2}, true},

        {"a > b", Person{"krabs", 1}, Person{"bob", 2}, false},

        {"a = a", Person{"plankton", 1}, Person{"plankton", 2}, false},

    }

    for _, testCase := range testCases {

        t.Run(testCase.desc, func(t *testing.T) {

            people := []Person{testCase.a, testCase.b}

            got := comparePeopleByName(people)(0, 1)

            if testCase.expected != got {

                t.Errorf("expected %v, got %v", testCase.expected, got)

            }

        })

    }

}

func TestComparePeopleByAge(t *testing.T) {

    testCases := []struct {

        desc     string

        a, b     Person

        expected bool

    }{

        {"a < b", Person{"sandy", 10}, Person{"patrick", 20}, true},

        {"a > b", Person{"sandy", 30}, Person{"patrick", 20}, false},

        {"a = b", Person{"sandy", 90}, Person{"patrick", 90}, false},

    }

    for _, testCase := range testCases {

        t.Run(testCase.desc, func(t *testing.T) {

            people := []Person{testCase.a, testCase.b}

            got := comparePeopleByAge(people)(0, 1)

            if testCase.expected != got {

                t.Errorf("expected %v, got %v", testCase.expected, got)

            }

        })

    }

}