您如何在主函数中测试代码

Question

Consider the following trivial main.go file:

package main

type myStruct struct {
   songs []string
}

func main() {
  s1 := myStruct{
    songs:[]string{"Master of Puppets", "Battery"}
  }
  foo(s1)
}

func foo(s myStruct) {
  // Does something with s
}

I get how I could test the foo function. But how could I test that the main function properly intializes the s1 struct and assert that the foo function get's called with s1 as an argument?

Answer 1

Why not try our most basic debug tool: printf.

package main

import "fmt"

type myStruct struct {
   songs []string
}

func main() {
  s1 := myStruct{songs:[]string{"Master of Puppets", "Battery"}}
  foo(s1)
}

func foo(s myStruct) {
  // Does something with s
  for i:=0;i<len(s.songs);i++ {
    fmt.Printf("s.songs[%d]=\"%s\"
",i, s.songs[i])
  }
}

output:

s.songs[0]="Master of Puppets"
s.songs[1]="Battery"

In case you really want to test if your structure was properly initialized inside your main function:

package main

import "fmt"

type myStruct struct {
   songs []string
}

func main() {
  s1 := myStruct{songs:[]string{"Master of Puppets", "Battery"}}
  foo(s1)
  for i:=0;i<len(s1.songs);i++ {
    fmt.Printf("s1.songs[%d]=\"%s\"
",i, s1.songs[i])
  }
}

func foo(s myStruct) {
  // Does something with s
  fmt.Printf("foo has finished its work!
")
}

output:

foo has finished its work!
s1.songs[0]="Master of Puppets"
s1.songs[1]="Battery"

If you want to make sure both main() and foo() are working with the same object, try this:

package main

import "fmt"

type myStruct struct {
   songs []string
}

func main() {
  s1 := myStruct{songs:[]string{"Master of Puppets", "Battery"}}
  foo(&s1)
  fmt.Printf("main() says: s1 lives in the address:%p
",&s1)
}

func foo(s *myStruct) {
  // Does something with s
  fmt.Printf("foo() says: s lives in the address:%p
",s)
}

output:

foo() says: s lives in the address:0x10434120
main() says: s1 lives in the address:0x10434120

Next time, try being more specific on your questions.

Cheers.