Go unit tests

Unit testing is what is used in the terminalgo testRun our custom test,The code writing requirements are as follows：

Go Language recommendation test files and source code files are placed together,测试文件以 _test.go 结尾,For example we need to test write inmytry.go里的Add函数,The test file name is mytry_test.go

The test function name is prefixed with the function to be testedTest,如要测试Add,The test function is namedTestAdd

When there are multiple functions to be tested,可以用-runto choose to run one of the use cases
go test -run TestAdd

-vThe test results for each use case can be displayed

multiple subtests

//mytry.go
package main

func Add(a int, b int) int {
    
    return a + b
}

func main(){
    
	ret:=Add(1,2)
}

//mytry_test.go
package main

import "testing"

func TestAdd(t *testing.T){
    
	cases:=[]struct{
    
		Name string
		A,B,Want int
	}{
    
		{
    "pos",2,3,5},
		{
    "neg",2,-4,-2},
		{
    "zero",2,-2,0},
	}

	for _,c:=range cases{
    
		t.Run(c.Name,func(t *testing.T){
    
			if Get:=Add(c.A,c.B);Get!=c.Want{
    
				t.Errorf("Name:%s,Want:%d,Get:%d",c.Name,c.Want,Get)
			}
		})
	}
}

go test -run TestAdd -v

=== RUN   TestAdd
=== RUN   TestAdd/pos
=== RUN   TestAdd/neg
=== RUN   TestAdd/zero
--- PASS: TestAdd (0.00s)
    --- PASS: TestAdd/pos (0.00s)
    --- PASS: TestAdd/neg (0.00s)
    --- PASS: TestAdd/zero (0.00s)
PASS
ok      goProject       0.002s

go test -run TestAdd/zero -v

=== RUN   TestAdd
=== RUN   TestAdd/zero
--- PASS: TestAdd (0.00s)
    --- PASS: TestAdd/zero (0.00s)
PASS
ok      goProject       0.002s

帮助函数

t.Helper(),Used to label this function as a helper function,When an error is reported, information to help the caller of the function will be output,rather than the internal information of the helper function.

// calc_test.go
package main

import "testing"

type calcCase struct{
     A, B, Expected int }

func createMulTestCase(t *testing.T, c *calcCase) {
    
	// t.Helper()
	if ans := Mul(c.A, c.B); ans != c.Expected {
    
		t.Fatalf("%d * %d expected %d, but %d got",
			c.A, c.B, c.Expected, ans)
	}

}

func TestMul(t *testing.T) {
    
	createMulTestCase(t, &calcCase{
    2, 3, 6})
	createMulTestCase(t, &calcCase{
    2, -3, -6})
	createMulTestCase(t, &calcCase{
    2, 0, 1}) // wrong case
}

在这里,We created a false test case on purpose,运行 go test,用例失败,The file and line number information where the error occurred will be reported：

$ go test
--- FAIL: TestMul (0.00s)
    calc_test.go:11: 2 * 0 expected 1, but 0 got
FAIL
exit status 1
FAIL    example 0.007s

可以看到,错误发生在第11行,That is, the helper function createMulTestCase 内部.18, 19, 20line calls this method,We were not able to determine which line the error occurred in the first time.Some helper functions may also be called from different functions,The error messages are all in the same place,Inconvenient to locate the problem.
If we annotate helper functions

func createMulTestCase(c *calcCase, t *testing.T) {
    
    t.Helper()
	t.Run(c.Name, func(t *testing.T) {
    
		if ans := Mul(c.A, c.B); ans != c.Expected {
    
			t.Fatalf("%d * %d expected %d, but %d got",
				c.A, c.B, c.Expected, ans)
		}
	})
}

运行 go test,报错信息如下,can be very clearly known,错误发生在第 20 行.

$ go test
--- FAIL: TestMul (0.00s)
    calc_test.go:20: 2 * 0 expected 1, but 0 got
FAIL
exit status 1
FAIL    example 0.006s

网络测试

Suppose you need to test something API 接口的 Handler 能够正常工作,例如 HelloHandler

func HelloHandler(w http.ResponseWriter, r *http.Request) {
    
	w.Write([]byte("hello world"))
}

package main

import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"testing"
)

func TestHelloHandler(t *testing.T) {
    
	req, err := http.NewRequest("GET", "/", nil)	//这里的urlIt seems like you can write whatever you want
	if err != nil {
    
		fmt.Println(err)
	}
	ret := httptest.NewRecorder()
	HelloHandler(ret, req)
	if ret.Body.String() != "hello world" {
    
		fmt.Println("handler erro")
	}
}

$ go test -run TestHelloHandler -v
=== RUN   TestHelloHandler
--- PASS: TestHelloHandler (0.00s)
PASS
ok      goProject       0.002s

测试覆盖率

go test -v -coverprofile=c.out

go tool cover -html=c.out

A page containing the test function will be generated in the browser,Green is covered,Red is not covered