end_to_end

End To End Testing

End to end allows us to test applications through the whole request cycle. Where unit testing is meant to just test a particular function, end to end tests will run the middleware, router, and other that a request my pass through.

package main

import (
	"fmt"
	"net/http"

	"github.com/codegangsta/negroni"
	"github.com/julienschmidt/httprouter"
)

func HelloWorld(res http.ResponseWriter, req *http.Request, p httprouter.Params) {
	fmt.Fprint(res, "Hello World")
}

func App() http.Handler {
	n := negroni.Classic()

	m := func(res http.ResponseWriter, req *http.Request, next http.HandlerFunc) {
		fmt.Fprint(res, "Before...")
		next(res, req)
		fmt.Fprint(res, "...After")
	}
	n.Use(negroni.HandlerFunc(m))

	r := httprouter.New()

	r.GET("/", HelloWorld)
	n.UseHandler(r)
	return n
}

func main() {
	http.ListenAndServe(":3000", App())
}

This is the test file. It should be placed in the same directory as your application and name main_test.go.

package main

import (
	"io/ioutil"
	"net/http"
	"net/http/httptest"
	"testing"
)

func Test_App(t *testing.T) {
	ts := httptest.NewServer(App())
	defer ts.Close()

	res, err := http.Get(ts.URL)
	if err != nil {
		t.Fatal(err)
	}

	body, err := ioutil.ReadAll(res.Body)
	res.Body.Close()

	if err != nil {
		t.Fatal(err)
	}

	exp := "Before...Hello World...After"

	if exp != string(body) {
		t.Fatalf("Expected %s got %s", exp, body)
	}
}

Exercises

1. Create another piece of middleware that mutates the status of the request.
2. Create a POST request and test that the request is properly handled.