测试Golang处理程序中是否调用了该方法

Question

I am implementing a API in Golang. I have a endpoint where I am calling a method with parameters of other package. Now I need to check that, that method has been called in the request.

Below is the small similar scenario what I am doing and what I am expecting.

My handler

package myPackage
import (
    "log"
    "github.com/myrepo/notifier" // my another package
)

func MyHandler(writer http.ResponseWriter, request *http.Request) { 
    // ...
    // ...

    notifier.Notify(4, "sdfsdf")

    // ...
    // ...

}

Testing handler

func TestMyHandler(t *testing.T) {
    // Here I want to 
    req, _ := http.NewRequest("GET", "/myendpoint", nil)
    // ... Want to test that notifier.Notify is called
    // ...
}

In the TestMyHandler, I want to check that notifier.Notify has called.

Findings

I tried to understand the AssertNumberOfCalls, func (*Mock) Called, and func (*Mock) MethodCalled but I am not sure how to use them :(.

I am a newbie in Golang and really exicted to do that. Please let me know if I missed anything or you may need more information for more understaing.

Answer 1

Want to test that notifier.Notify is called.

No you don't. You are interested in that the handler does what it should do and this seems to consist of two things:

1. Return the right response (easy to test with a net/http/httptest.ResponseRecorder), and

2. Has some noticeable side effect, here issue some notification.

To test 2. you test that the notification was issued, not that some function was called. Whatever notify.Notify results in (e.g. a database entry, a file, some HTTP call) should be tested. Formally this is no longer unit testing but testing for side effects is never strict unit testing.

What you can do: Wrap your handler logic into some object and observe that objects state. Ugly. Don't.