Golang单元测试HTTP处理程序

Question

I want to make a simple server that can receive web hook requests from services and deal with them for me. And for fun I wanted to build that in Go, since that sounds like a nice language and this is a simple project to start with.

The server seems to be working fine, but I can't get my unittest to work. On inspection it seems that every url gives a 404. What am I doing wrong?

main.go

package main

import (
    "fmt"
    "log"
    "net/http"
)

func pingHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "{\"check\": \"online\"}")
}

func main() {
    // Start server
    log.Print("Starting server")
    http.HandleFunc("/ping", pingHandler)
    log.Fatal(http.ListenAndServe(":7080", nil))
}

main_test.go

package main

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

func TestPingHandler(t *testing.T) {
    req, err := http.NewRequest("GET", "/ping", nil)
    if err != nil {
        t.Fatal(err)
    }
    rr := httptest.NewRecorder()
    http.DefaultServeMux.ServeHTTP(rr, req)

    status := rr.Code
    fmt.Println(status)
}

Answer 1

Your handler is registered in main , but main is not invoked when you're running unit tests. So, when you try to test via DefaultMux , no handlers are registered, and you get a 404. However, generally you test the handler, not the mux; so instead of this line:

http.DefaultServeMux.ServeHTTP(rr, req)

You would instead test:

pingHandler(rr, req)

Which will work even though main is not executed to register the handler, because you're now testing the handler directly.

You should also use httptest.NewRequest to create requests for testing; http.NewRequest is for creating requests for use in a Client .