Go中代码性能测试

shiyd, • Go
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1、传统测试

2、表格驱动测试

这里以勾股函数为例：

triangle.go

package test_example

import (
	"fmt"
	"math"
)

func triangle() {
	var a, b int = 3, 4
	fmt.Println(calcTriangle(a, b))
}

func calcTriangle(a, b int) int {
	var c int
	c = int(math.Sqrt(float64(a*a + b*b)))
	return c
}

triangle_test.go

package test_example

import "testing"

func TestTriangle(t *testing.T) {
	// 测试数据
	tests := []struct{ a, b, c int }{
		{3, 4, 5},
		{5, 12, 13},
		{8, 15, 17},
		{12, 35, 3},    // fail：calcTriangle(12, 35) got 37; expected 3
		{30000, 40000, 50000},
	}
	
	// 数据和测试逻辑分离
	for _, tt := range tests {
		if actual := calcTriangle(tt.a, tt.b); actual != tt.c {
			t.Errorf("calcTriangle(%d, %d) got %d; expected %d", tt.a, tt.b, actual, tt.c)
		}
	}
}

3、代码覆盖率和性能测试

在 Goland 代码编辑器中集成了各种测试方法，如下图3-1:

命令行测试代码覆盖率

csgo/test_exmaple on  main [✘!+] via 🐹 v1.19.4 
❯ go test
PASS
ok      github.com/shiiiiyd/csgo/test_exmaple   0.806s

代码覆盖率测试命令生成out文件

csgo/test_exmaple on  main [✘!+] via 🐹 v1.19.4 
❯ go test -coverprofile=c.out
PASS
coverage: 60.0% of statements
ok      github.com/shiiiiyd/csgo/test_exmaple   0.817s

go tool cover 其他命令

csgo/test_exmaple on  main [✘!+?] via 🐹 v1.19.4 
❯ go tool cover
Usage of 'go tool cover':
Given a coverage profile produced by 'go test':
        go test -coverprofile=c.out

Open a web browser displaying annotated source code:
        go tool cover -html=c.out

Write out an HTML file instead of launching a web browser:
        go tool cover -html=c.out -o coverage.html

Display coverage percentages to stdout for each function:
        go tool cover -func=c.out

Finally, to generate modified source code with coverage annotations
(what go test -cover does):
        go tool cover -mode=set -var=CoverageVariableName program.go

Flags:
  -V    print version and exit
  -func string
        output coverage profile information for each function
  -html string
        generate HTML representation of coverage profile
  -mode string
        coverage mode: set, count, atomic
  -o string
        file for output; default: stdout
  -var string
        name of coverage variable to generate (default "GoCover")

  Only one of -html, -func, or -mode may be set.

这里使用 go tool cover -html=c.out 命令查看代码覆盖率，显示为html页面，如图3-2所示：

Benchmark 性能测试，测试代码如下：

func BenchmarkTriangle(b *testing.B) {
	tests := []struct{ a, b, c int }{
		{3, 4, 5},
		{5, 12, 13},
		{8, 15, 17},
		{12, 35, 37},
		{30000, 40000, 50000},
	}
	for i := 0; i < b.N; i++ {
		for _, tt := range tests {
			actual := calcTriangle(tt.a, tt.b)
			if actual != tt.c {
				b.Errorf("calcTriangle(%d, %d) got %d; expected %d", tt.a, tt.b, actual, tt.c)
			}
		}
	}

}

测试结果：执行了285965554次，每次执行花费的时间是 4.136 纳秒

goos: darwin
goarch: arm64
pkg: github.com/shiiiiyd/csgo/test_exmaple
BenchmarkTriangle
BenchmarkTriangle-8   	285965554	         4.136 ns/op
PASS

命令行测试：

❯ go test -bench . 
goos: darwin
goarch: arm64
pkg: github.com/shiiiiyd/csgo/test_exmaple
BenchmarkTriangle-8     281769649                4.144 ns/op
PASS
ok      csgo/test_exmaple   1.901s

使用 go test -bench . -cpuprofile=cpu.out 命令查看，输出一个cpu.out文件，该文件是二进制文件，无法直接查看，可以使用 go tool pprof cpu.out 命令进入到交互命令界面，然后输入 web 之后就会生成一个svg文件，可以在浏览器中查看该文件的，文件内容如图3-3所示，该图生成需要提前安装 Graphviz 软件。

❯ go test -bench . -cpuprofile=cpu.out
goos: darwin
goarch: arm64
pkg: github.com/shiiiiyd/csgo/test_exmaple
BenchmarkTriangle-8     281105055                4.148 ns/op
PASS
ok      csgo/test_exmaple   2.514s

❯ go tool pprof  cpu.out
Type: cpu
Time: Jan 1, 2023 at 4:21pm (CST)
Duration: 1.72s, Total samples = 1.44s (83.91%)
Entering interactive mode (type "help" for commands, "o" for options)
(pprof) web
(pprof)

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