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.