前置条件：
1、文件名须以"_test.go"结尾
2、方法名须以"Test"打头，并且形参为 (t *testing.T)
举例：/hello_test.go
package main
import (
"testing"
"fmt"
)
func TestHello(t *testing.T) {
fmt.Println("TestHello")
}
func TestWorld(t *testing.T) {
fmt.Println("TestWorld")
}
测试整个文件：$ go test -v hello_test.go
=== RUN TestHello
TestHello
--- PASS: TestHello (0.00s)
=== RUN TestWorld
TestWorld
--- PASS: TestWorld (0.00s)
PASS
ok command-line-arguments 0.007s
测试单个函数：$ go test -v hello_test.go -test.run TestHello
=== RUN TestHello
TestHello
--- PASS: TestHello (0.00s)
PASS
ok command-line-arguments 0.008s
