🤗 Testing a gofiber proxy handler

[dominicfollett]

Question description
Hi there, thank you for the awesome Gofiber package. I have a question about testing Gofiber as a proxy. Small caveat: I am somewhat new to Go and Gofiber.

I have implemented a small proxy service using Gofiber, and I used your tests here as reference for writing my own tests.

I'd like to know if this the recommend or correct approach to testing Gofiber as a proxy? Or if I should be mocking out the proxying somehow.

Handler Function

func BulkEventsHandler(c *fiber.Ctx) error {
	url := buildURL(cfg().Proxy.Forward.Events, c.Path())

	// Before we do the proxy save the body to a DB
	// in a goroutine so that it doesn't block
	go saveEvent(copyBody(c.Request().Body()))

	if err := proxy.Do(c, url); err != nil {
		logrus.Error("Proxy to Foo failed: ", err)
		return err
	}

	// Remove Server header from response
	c.Response().Header.Del(fiber.HeaderServer)
	return nil
}

TestFunction

func TestBulkEventsHandler(t *testing.T) {
	// Parallel signals that this test is to be run in parallel
	// with (and only with) other parallel tests.
	t.Parallel()

	// Create a new fiber app
	app := fiber.New()

	// Make sure the proxy middleware doesn't have problems with
	// self-signed certificates
	proxy.WithTlsConfig(&tls.Config{
		InsecureSkipVerify: true,
	})

	// Create a fake server for handling the proxied request
	_, addr := createProxyTestServer(
		func(c *fiber.Ctx) error {
			return c.SendString("forwarded")
		}, t, "/events/bulk/:id",
	)

	// Mock out the function that returns config - there must be a better way
	// Adjust the config so that we're forwarding requests to our new server
	cfg = func() config.Config {
		return config.Config{
			Proxy: config.Proxy{
				Forward: config.Forward{
					Events: addr,
				},
			},
		}
	}

	// Set up the route, and specify the handler under test
	app.Post("/events/bulk/:id", BulkEventsHandler)

	// Create some dummy event data
	bodyReader := strings.NewReader(`{"user": "12124", "data": "blah"}`)

	// Test our proxy
	resp, err := app.Test(
		httptest.NewRequest(
			"POST",
			"/events/bulk/1234",
			bodyReader,
		),
	)

	utils.AssertEqual(t, nil, err)
	utils.AssertEqual(t, fiber.StatusOK, resp.StatusCode)

	b, err := ioutil.ReadAll(resp.Body)
	utils.AssertEqual(t, nil, err)
	utils.AssertEqual(t, "forwarded", string(b))
}

Is the following necessary? Should I instead somehow mock proxy.Do?

Server that handles the proxied request

func createProxyTestServer(handler fiber.Handler, t *testing.T, path string) (*fiber.App, string) {
	// Helper marks the calling function as a test helper function.
	t.Helper()

	// Create a new fiber app that will act as the server
	target := fiber.New(fiber.Config{DisableStartupMessage: true})
	// Set up the route that we will expect to be proxied to us
	target.Post(path, handler)

	// Create a listener on a random unused port
	ln, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	utils.AssertEqual(t, nil, err)

	// Generate self-signed certs for this server
	serverTLSConf, _, err := getTLSConfigs()
	utils.AssertEqual(t, nil, err)

	// Update the listener with the certs
	ln = tls.NewListener(ln, serverTLSConf)

	// This has to be run in a goroutine otherwise it will block
	go func() {
		// set the app's listener
		utils.AssertEqual(t, nil, target.Listener(ln))
	}()

	// Give the app time to get ready - this isn't ideal
	time.Sleep(2 * time.Second)
	addr := ln.Addr().String()

	return target, addr
}

Additionally, I'd like to test that the saveEvent method in my handler gets called, but the only way I think I could do that is if I altered the call signature of the handler e.g. func(c * fiber.Ctx, db *DB) where I could pass in a mock instead. But I don't think that is possible. Any recommendation would be most welcome. Thank you.

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