最少的http服务测试而无需重新设置路由？

Question

Say I have a very simple Web service.

func main() {
    http.HandleFunc("/", sanityTest)
    log.Fatal(http.ListenAndServe(":8000", nil))
}

If I want to test it, I could minimally just have:

func ExampleTest() {
        server := httptest.NewServer(http.DefaultServeMux)
        defer server.Close()

        resp, err := http.Get(server.URL)
        if err != nil {
                log.Fatal(err)
        }
        body, _ := ioutil.ReadAll(resp.Body)

        fmt.Println(resp.StatusCode)
        fmt.Println(resp.Header.Get("Content-Type"))
        fmt.Println(string(body))

        // Output:
        // 200
        // text/plain; charset=utf-8
        // OK

}

But that will result in a 404, since it doesn't know about the routes. So what I've seen main_test.go code do, is re-setup the handles in the test file's init, like so:

func init() {
    http.HandleFunc("/", sanityTest)
}

Which leads to duplication, and inevitably I have to create a function in main.go like:

func setupRoutes() {
        http.HandleFunc("/", sanityTest)
}

Which I find a little ugly. Am I missing a trick to instantiate the routes from main.go and avoid the init?

Answer 1

You can re-use routes between tests and main.go file, also it's helpful if you want to mock something in your handlers (add a new argument to router() func below)

main.go:

func sanityTest(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "%s", "sanity test")
}

func router() *http.ServeMux {
    h := http.NewServeMux()
    h.HandleFunc("/", sanityTest)
    return h
}

func main() {
    http.ListenAndServe(":8080", router())
}

main_test.go:

func TestSanity(t *testing.T) {
    tests := []struct {
        name string
        uri  string
        want string
    }{
        {"1", "/", "sanity test"},
    }

    ts := httptest.NewServer(router())
    defer ts.Close()

    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            url := ts.URL + tt.uri
            resp, _ := http.Get(url)
            respBody, _ := ioutil.ReadAll(resp.Body)
            resp.Body.Close()

            got := string(respBody)
            if got != tt.want {
                t.Errorf("got %s, Want %s", got, tt.want)
            }
        })
    }
}