簡介

日常開發中,測試是不能缺少的.

Go 標準庫中有一個叫做 testing 的測試框架,可以用於單元測試和效能測試.

它是和命令 go test 整合使用的.

測試檔案是以後綴 _test.go 命名的,通常和被測試的檔案放在同一個包中.

單元測試

單元測試的格式形如:

func TestAbs(t *testing.T) {
 got := Abs(-1)
 if got != 1 {
  t.Errorf("Abs(-1) = %d; want 1",got)
 }
}

在 util 目錄下建立一個檔案 util_test.go,新增一個單元測試:

package util

import "testing"

// 普通的測試
func TestGenShortID(t *testing.T) {
 shortID,err := GenShortID()
 if shortID == "" || err != nil {
 t.Error("GenShortID failed")
 }
}

然後,在根目錄下執行 go test -v ./util/,測試結果如下:

root@592402321ce7:/workspace# go test -v ./util/
=== RUN  TestGenShortID
--- PASS: TestGenShortID (0.00s)
PASS
ok   tzh.com/web/util    0.006s

效能測試

效能測試的結果形如:

func BenchmarkHello(b *testing.B) {
 for i := 0; i < b.N; i++ {
  fmt.Sprintf("hello")
 }
}

在 util_test.go 新增效能測試:

// 效能測試
func BenchmarkGenShortID(b *testing.B) {
 for i := 0; i < b.N; i++ {
 GenShortID()
 }
}

執行結果如下(使用 --run=none 避免執行普通的測試函式,因為一般不可能有函式名匹配 none):

root@592402321ce7:/workspace# go test -v -bench="BenchmarkGenShortID$" --run=none ./util/
goos: linux
goarch: amd64
pkg: tzh.com/web/util
BenchmarkGenShortID-2       507237       2352 ns/op
PASS
ok   tzh.com/web/util    1.229s

這說明,平均每次執行 GenShortID() 需要 2352 納秒.

效能分析

執行測試的時候,可以指定一些引數,生成效能檔案 profile.

-blockprofile block.out
  Write a goroutine blocking profile to the specified file
  when all tests are complete.
  Writes test binary as -c would.

-blockprofilerate n
  Control the detail provided in goroutine blocking profiles by
  calling runtime.SetBlockProfileRate with n.
  See 'go doc runtime.SetBlockProfileRate'.
  The profiler aims to sample,on average,one blocking event every
  n nanoseconds the program spends blocked. By default,if -test.blockprofile is set without this flag,all blocking events
  are recorded,equivalent to -test.blockprofilerate=1.

-coverprofile cover.out
  Write a coverage profile to the file after all tests have passed.
  Sets -cover.

-cpuprofile cpu.out
  Write a CPU profile to the specified file before exiting.
  Writes test binary as -c would.

-memprofile mem.out
  Write an allocation profile to the file after all tests have passed.
  Writes test binary as -c would.

-memprofilerate n
  Enable more precise (and expensive) memory allocation profiles by
  setting runtime.MemProfileRate. See 'go doc runtime.MemProfileRate'.
  To profile all memory allocations,use -test.memprofilerate=1.

-mutexprofile mutex.out
  Write a mutex contention profile to the specified file
  when all tests are complete.
  Writes test binary as -c would.

-mutexprofilefraction n
  Sample 1 in n stack traces of goroutines holding a
  contended mutex.

使用下面的命令,生成 CPU 的 profile:

go test -v -bench="BenchmarkGenShortID$" --run=none -cpuprofile cpu.out ./util/

當前目錄下,應該會生成 cpu.out 檔案和 util.test 檔案.

使用下面的命令,觀察耗時操作:

# 進入互動模式
go tool pprof cpu.out
top

安裝 Graphviz 後可以生成視覺化的分析圖.

apt install graphviz
go tool pprof -http=":" cpu.out

測試覆蓋率

root@592402321ce7:/workspace# go test -v -coverprofile=cover.out ./util/
=== RUN  TestGenShortID
--- PASS: TestGenShortID (0.00s)
PASS
coverage: 9.1% of statements
ok   tzh.com/web/util    0.005s coverage: 9.1% of statements

root@592402321ce7:/workspace# go tool cover -func=cover.out
tzh.com/web/util/util.go:12:  GenShortID   100.0%
tzh.com/web/util/util.go:17:  GetReqID    0.0%
tzh.com/web/util/util.go:22:  TimeToStr    0.0%
tzh.com/web/util/util.go:30:  GetTag     0.0%
total:             (statements)  9.1%

使用 -coverprofile=cover.out 選項可以統計測試覆蓋率.使用 go tool cover -func=cover.out 可以檢視更加詳細的測試覆蓋率結果,
統計每個函式的測試覆蓋率.

總結

測試是開發中非常重要的一個環節,用於保證軟體質量,切不可偷懶.

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