Golang 测试

前言

关于 Go 测试,我们应该知道测试方式(或者说测试手段)、测试对象及测试原因。

How 测试方式

测试实现

举个例子。针对字符串分割函数(如下),实现单元测试。

package goTest
import "strings"
// Split slices s into all substrings separated by sep and
// returns a slice of the substrings between those separators.
func Split(s, sep string) []string {
 var result []string
 i := strings.Index(s, sep)
 for i > -1 {
 result = append(result, s[:i])
 s = s[i+len(sep):]
 i = strings.Index(s, sep)
 }
 return append(result, s)
}

在当前目录下且一样的包名 goTest ,写一个简单的 go 测试函数,如下:

package goTest
import (
 "reflect"
 "testing"
)
func TestSplit(t *testing.T) {
 got := Split("a/b/c", "/")
 want := []string{"a", "b", "c"}
 if !reflect.DeepEqual(want, got) {
 t.Fatalf("expected: %v, got: %v", want, got)
 }
}

测试函数必须以 Test 开头, 且必须携带一个 *testing.T 参数。 t *testing.T 提供改测试函数的打印、跳过、失败功能。

测试执行

当前目录下,执行 go test ,输出如下:

> go test
PASS
ok goTest 0.005s

如果项目中存在多个 package ,若要执行所有包的测试可以在项目根目录下使用 go test ./... ,输出如下(例子:github.com/mattn/go-sqlite3):

> go test ./...
ok github.com/mattn/go-sqlite3 14.693s
? github.com/mattn/go-sqlite3/upgrade [no test files]

代码测试覆盖率

还是以字符串分割函数为例, 获取当前代码测试覆盖率方式如下:

> go test -coverprofile=c.out
PASS
coverage: 100.0% of statements
ok goTest 0.005s

数据显示覆盖率为 100% 。若要以 HTML 方式显示可以使用命令 go tool cover -html=c.out 。

【tip】 一行命令 cover 获取当前目录下的代码测试覆盖度。 在 ~/.bashrc 中添加如下命令:

cover () {
 local t=$(mktemp -t cover)
 go test $COVERFLAGS -coverprofile=$t $@ \
 && go tool cover -func=$t \
 && unlink $t
}

执行后获取的测试覆盖度结果如下:

> cover
PASS
coverage: 100.0% of statements
ok goTest 0.008s
goTest/wwg_split.go:7: Split 100.0%
total: (statements) 100.0%

问题:测试覆盖率 100% ,结束了?

多个测试用例的情况下,使用表组测试用例装填。更改 TestSplit 如下:

func TestSplit(t *testing.T) {
 tests := []struct{
 input string
 sep string
 want []string
 }{
 {input: "a/b/c", sep: "/", want: []string{"a", "b", "c"}},
 {input: "a/b/c", sep: ",", want: []string{"a/b/c"}},
 {input: "a/b/c/", sep: "/", want: []string{"a", "b", "c"}}, // trailing sep
 {input: "abc", sep: "/", want: []string{"abc"}},
 }
 for _, tc := range tests {
 got := Split(tc.input, tc.sep)
 if !reflect.DeepEqual(tc.want, got) {
 t.Fatalf("expected: %v, got: %v", tc.want, got)
 }
 }
}

增加测试用例 trailing sep 后,执行测试,结果如下:

> go test
--- FAIL: TestSplit (0.00s)
 wwg_split_test.go:23: expected: [a b c], got: [a b c ]
FAIL
exit status 1
FAIL goTest 0.005s

根据该结果很难一下子在表组测试用例中查出是哪条。可以将 表组测试用例实现改为 map 形式 ,具体如下:

func TestSplit(t *testing.T) {
 tests := map[string]struct{
 input string
 sep string
 want []string
 }{
 "simple": {input: "a/b/c", sep: "/", want: []string{"a", "b", "c"}},
 "wrong sep": {input: "a/b/c", sep: ",", want: []string{"a/b/c"}},
 "trailing sep": {input: "a/b/c/", sep: "/", want: []string{"a", "b", "c"}},
 "no sep": {input: "abc", sep: "/", want: []string{"abc"}},
 }
 for name, tc := range tests {
 got := Split(tc.input, tc.sep)
 if !reflect.DeepEqual(tc.want, got) {
 t.Errorf("%s expected: %v, got: %v", name, tc.want, got)
 }
 }
}

执行测试结果如下:

> go test
--- FAIL: TestSplit (0.00s)
 wwg_split_test.go:23: trailing sep expected: [a b c], got: [a b c ]
FAIL
exit status 1
FAIL goTest 0.005s

Sub tests 使用,及 '%#v' format 使用,更改 TestSplit 如下:

func TestSplit(t *testing.T) {
 tests := map[string]struct{
 input string
 sep string
 want []string
 }{
 "simple": {input: "a/b/c", sep: "/", want: []string{"a", "b", "c"}},
 "wrong sep": {input: "a/b/c", sep: ",", want: []string{"a/b/c"}},
 "trailing sep": {input: "a/b/c/", sep: "/", want: []string{"a", "b", "c"}},
 "no sep": {input: "abc", sep: "/", want: []string{"abc"}},
 }
 for name, tc := range tests {
 t.Run(name, func(t *testing.T) {
 got := Split(tc.input, tc.sep)
 if !reflect.DeepEqual(tc.want, got) {
 t.Fatalf("%s expected: %#v, got: %#v", name, tc.want, got)
 }
 })
 }
}

测试结果如下:

> go test
--- FAIL: TestSplit (0.00s)
 --- FAIL: TestSplit/trailing_sep (0.00s)
 wwg_split_test.go:24: trailing sep expected: []string{"a", "b", "c"}, got: []string{"a", "b", "c", ""}
FAIL
exit status 1
FAIL goTest 0.005s

更好的打印格式,可以访问:

• https://github.com/k0kubun/pp
• https://github.com/davecgh/go-spew
• https://github.com/google/go-cmp

使用 google/go-cmp 优化打印, 更改 TestSplit 如下:

 for name, tc := range tests {
 t.Run(name, func(t *testing.T) {
 got := Split(tc.input, tc.sep)
 diff := cmp.Diff(tc.want, got)
 if diff != "" {
 t.Fatalf(diff)
 }
 })
 }

执行测试结果如下:

> go test
--- FAIL: TestSplit (0.00s)
 --- FAIL: TestSplit/trailing_sep (0.00s)
 wwg_split_test.go:29: []string{
 "a",
 "b",
 "c",
 + "",
 }
FAIL
exit status 1
FAIL goTest 0.005s

修复bug后 Split 代码如下:

// Split slices s into all substrings separated by sep and
// returns a slice of the substrings between those separators.
func Split(s, sep string) []string {
 var result []string
 i := strings.Index(s, sep)
 for i > -1 {
 result = append(result, s[:i])
 s = s[i+len(sep):]
 i = strings.Index(s, sep)
 }
 if len(s) > 0 {
 result = append(result, s)
 }
 return result**
}

执行测试,结果如下:

> go test
PASS
ok goTest 0.006s
> cover
PASS
coverage: 100.0% of statements
ok goTest 0.006s
goTest/wwg_split.go:7: Split 100.0%
total: (statements) 100.0%

What 测试对象

Q_1:Go 应该测试所有因子吗?

A_1:显然不是。

Q_2:何时编写测试? 1.编码完成后? 2.编码前? 3.其他人遍写测试,像QA、TE? 4.项目设计人员编写测试?

A_2:编码的同时编写测试代码(TDD)Article TheThreeRulesOfTdd

Q_3:C 单元测试对象是 function ,Java 单元测试对象是 Class ,类内部的方法, Go 的单元测试对象是?

A_3:package 。测试行为,而非实施。 "The public API of a package declare this is what(行为) I do, not this is how(实施) I do it."

Why 测试原因

即使你不做代码测试,别人也会做。自己发现 issues 总比别人发现来得好,不是吗?

1. 大部分的测试(自动化)应该是开发人员自己做。
2. 手工测试不应该是你测试的主体部分,因为手工测试的复杂度为O(n)
3. 测试可以确保您始终可以运送主分支
4. 测试确定软件行为(做什么、不做什么)
5. 测试让你有信心修改他人的代码

总结

• You should write tests.
• You should write tests at the same time as you write your code.
  Each Go package is a self contained unit.
• Your tests should assert the observable behaviour of your package, not its implementation.
• You should design your packages around their behaviour, not their implementation.

【注】部分资料源于GopherChina 2019 - 'How to write testable code'
本文链接:GO TESTING;HOW,WHAT,WHY

本文来自:简书

感谢作者:

查看原文:Golang 测试

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