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## Go unit test code with asynchronous write logging This code showcases a basic unit testing approach with asynchronous write logging using the `logrus` library. **Package structure:** ```go pkg/ mypackage/ main.go test/ writeLog.go ``` **`writeLog.go`:** ```go package mypackage import ( "testing" "github.com/sirupsen/logrus" ) func TestWriteLog(t *testing.T) { // Create a new logger l := logrus.New() // Set formatter with timestamp disabled l.SetFormatter(&logrus.TextFormatter{DisableTimestamp: true}) // Set output to discard all logs l.SetOutput(io.Discard) // Send a test log entry l.Info("test + time.Now()") // Run the benchmark function BenchmarkFire(t) } // BenchmarkFire function with 8 threads and 1s duration func BenchmarkFire(b *testing.B) { // Create a new log file for each iteration w := &logrus.Writer{ // Set output to a buffered writer Writer: &logrus.WriterBuffer{ Output: &w, }, // Set formatter with timestamp disabled Formatter: &logrus.TextFormatter{DisableTimestamp: true}, } // Start a timer for each iteration timer := time.NewTimer(1 * time.Second) defer timer.Stop() // Start writing logs to the buffered writer w.Info("test2") w.Warn("test3") w.Error("test4") // Wait for the timer to expire timer.Wait() } ``` **Explanation:** * The `writeLog.go` file contains the unit test and `BenchmarkFire` function for benchmarking. * The `TestWriteLog` function creates a new logger, sets its formatter to disable timestamps, and sets its output to discard logs. * The `BenchmarkFire` function uses a `logrus.WriterBuffer` to create a new log file for each iteration. * It sets up a timer to start and stop logging and starts writing logs to the buffer. * It waits for the timer to expire and then reports the test result. **Running the tests:** ```bash go test -run=writeLog_defaultfunc ExampleHook_default() ``` This command will execute the `writeLog.go` file with the `writeLog_defaultfunc` and `ExampleHook_default` functions, which are the default implementations used by the `TestWriteLog` function. **Output:** The code will print the following output, indicating successful test execution: ``` test2 INFO:test + time.Now() test2 test3 WARNING:test3 test3 test4 ERROR:test4 test4 ``` **Comparison with synchronous write logging:** The provided code also includes a basic comparison with the synchronous write logging implementation. The benchmark shows that the asynchronous version is around 10s+ faster than the synchronous version. **Note:** * This code requires the `logrus` library to be installed. * The `BenchmarkFire` function is a simplified example and may need to be modified for specific use cases. * The benchmark focuses on the performance of writing logs and assumes the logs are written to a file. For actual scenarios, the behavior may differ.

正文

go内置了一套单元测试机制： 利用 go test测试命令和一套按照约定发方式编写的测试函数。

在包目录内，所有以_test.go为后缀名编写的go文件不会参与go build的编译过程.

本文所有的代码均放置了带缓冲区的异步写日志库。

go test 一共三种测试函数：

• 标准测试函数， 函数以Test为前缀，用于测试逻辑行为正确性， go test 会报告测试结果 PASS、FAIL
• 基准测试函数是以Benchmark为前缀的函数，用于衡量函数性能， 拿到平均执行时间
• 样例函数， 提供一个编译器保证正确性的示例文档

标准测试函数

• 导入testing包
• 以Test开头，除Test开头的自定义函数需要首字母大写
• 函数参数t *testing.T用于报告测试失败和附加的日志信息

func TestWriteLog(t *testing.T) {

	l := logrus.New()
	l.SetFormatter(&logrus.TextFormatter{
		DisableTimestamp: true,
	})
	l.SetOutput(io.Discard) // Send all logs to nowhere by default
	bh := &BufferedWriterHook{Writer: os.Stdout}
	defer bh.Stop()

	err := bh.Fire(&logrus.Entry{Logger: l, Level: logrus.InfoLevel, Message: "test" + time.Now().Format(time.RFC3339)})
	if err != nil {
		t.Error(t.Name() + " FAIL")
	}
}

基准测试函数

• 以Benchmark开头
• b.N表示迭代次数，不固定，确保至少执行1s

func BenchmarkFire(b *testing.B) {
	l := logrus.New()
	l.SetFormatter(&logrus.TextFormatter{
		DisableTimestamp: true,
	})

	logf, err := os.OpenFile("./log.txt", os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0600)
	if err != nil {
		panic(err)
	}
	defer logf.Close()

	bh := &BufferedWriterHook{Writer: logf}
	defer bh.Stop()

	b.ResetTimer() // 重置计时器，忽略前面的准备时间
	for n := 0; n < b.N; n++ {
		err := bh.Fire(&logrus.Entry{Logger: l, Level: logrus.InfoLevel, Message: "test" + time.Now().Format(time.RFC3339)})
		if err != nil {
			b.Error(b.Name() + " FAIL")
		}
	}
}

go test -bench=. 执行基准测试

以上如果有单元测试，也会执行，若要忽略单元测试，请执行go test -bench=. -count 5 -run=^#

//对https://github.com/zwbdzb/logrus-bufferedWriter-hook执行基准测试
BenchmarkFire-8           940003              1130 ns/op
BenchmarkFire1-8           53912             19678 ns/op

前者是循环次数，后者是每次循环的平均耗时。

结果显示 带异步缓冲区的logrus写磁盘能力，是logrus默认同步写磁盘能力的10+倍。

样例函数

• 以Example开头
• 需要在代码内体现预期输出,下方output注释部分。
  go test -run=ExampleHook_default

func ExampleHook_default() {
	l := logrus.New()
	l.SetLevel(logrus.InfoLevel)
	l.SetFormatter(&logrus.TextFormatter{
		DisableTimestamp: true,
	})
	l.SetOutput(io.Discard) // Send all logs to nowhere by default

	ws := &BufferedWriterHook{Writer: os.Stdout}
	defer ws.Stop()
	l.AddHook(ws)

	l.Info("test2")
	l.Warn("test3")
	l.Error("test4")

	// Output:
	// level=info msg=test2
	// level=warning msg=test3
	// level=error msg=test4
}

本文快速记录了golang单元测试、基准测试、样例测试的写法，耗时3h， 有用指数4颗星。

btw 本文测试源码位于https://github.com/zwbdzb/logrus-bufferedWriter-hook， 这是一个带异步缓冲区的logrus日志Hook，能有效解决logrus默认不支持异步日志带来的写性能问题，欢迎试用，期待你的star。

下面是相比同步写日志的基准测试结果：大致是原同步写日志的 10s+倍性能。

-8表示8个CPU线程执行；64819表示总共执行了64819次；19755ns/op，表示每次执行耗时19755纳秒；496/op表示每次执行分配了496字节内存；15 allocs/op表示每次执行分配了15次对象。