Simplifying testing in Go via a few help functions

testingin.go

// Given a simple web server sample:

func main() {

	config := "this is some config"
	http.Handle("/", HandleDefaultRoute(config))
	http.ListenAndServe(":8080", nil)
}

func HandleDefaultRoute(config string) http.HandlerFunc {
	return func(rw http.ResponseWriter, req *http.Request) {
		if config == "" {
			rw.WriteHeader(http.StatusBadRequest)
			return
		}

		rw.Write([]byte(config))
	}
}

// We can write small, easy to read tests:

func Test_default_route_with_valid_config(t *testing.T) {

	respRec, req := NewRecordabelGetRequest(t, "/")
	HandleDefaultRoute("this is a test")(respRec, req)
 	equals(t, http.StatusOK, respRec.Code)
}

func Test_default_route_with_invalid_config(t *testing.T) {

	respRec, req := NewRecordabelGetRequest(t, "/")
	HandleDefaultRoute("")(respRec, req)
	equals(t, http.StatusBadRequest, respRec.Code)
}

// Using some utility functions as described below:

func NewRecordabelGetRequest(t *testing.T, route string) (*httptest.ResponseRecorder, *http.Request) {
	respRec := httptest.NewRecorder()
	req, err := http.NewRequest("GET", route, nil)
	if err != nil {
		t.Fatal(err)
	}
	return respRec, req
}

func NewRecordabelPostRequest(t *testing.T, route string, dto interface{}) (*httptest.ResponseRecorder, *http.Request) {

	b := make([]byte, 0)
	buf := bytes.NewBuffer(b)
	json.NewEncoder(buf).Encode(&dto)

	respRec := httptest.NewRecorder()
	req, err := http.NewRequest("POST", route, buf)
	if err != nil {
		t.Fatal(err)
	}
	return respRec, req
}

// assert fails the test if the condition is false.
func assert(tb testing.TB, condition bool, msg string, v ...interface{}) {
	if !condition {
		_, file, line, _ := runtime.Caller(1)
		fmt.Printf("\033[31m%s:%d: "+msg+"\033[39m\n\n", append([]interface{}{filepath.Base(file), line}, v...)...)
		tb.FailNow()
	}
}

// ok fails the test if an err is not nil.
func ok(tb testing.TB, err error) {
	if err != nil {
		_, file, line, _ := runtime.Caller(1)
		fmt.Printf("\033[31m%s:%d: unexpected error: %s\033[39m\n\n", filepath.Base(file), line, err.Error())
		tb.FailNow()
	}
}

// equals fails the test if exp is not equal to act.
func equals(tb testing.TB, exp, act interface{}) {
	if !reflect.DeepEqual(exp, act) {
		_, file, line, _ := runtime.Caller(1)
		fmt.Printf("\033[31m%s:%d:\n\n\texp: %#v\n\n\tgot: %#v\033[39m\n\n", filepath.Base(file), line, exp, act)
		tb.FailNow()
	}
}