vilimblog - Page 38 of 40 -

Testing REST API with LearnBoost’s Tobi + Vows.js

I've been looking for a clean, framework-independent way of doing white-box API testing using Node.js. For a long while, the things that popped up when doing a quick scan of the Node Package Manager package lists weren't ticking all of the right boxes: zombie.js is going for a full browser simulation but doesn't provide a simple Browser.post() method (you have to use selectors to find the form.submit button and then fire a click() on it), Node's native http.Client is too low-level and doesn't do cookies, and various other http request wrappers weren't quite cutting it either. I think I've found a solution for this particular version of the problem: LearnBoost's Tobi combined with Vows.js is letting me do clean REST API testing, with a minimum of hassle, and all the built-in sugar-coated goodness of should.js fluent assertions. For example:

var HOST  = 'localhost';
var PORT  = 80;
var API   = "/api/user/create";

var tobi   = require('tobi'),
    vows   = require('vows'),
    assert = require('assert');

var newbie = function() { return tobi.createBrowser(PORT, HOST) };

// -------------------------------------------------------------
// Macros.
// -------------------------------------------------------------

var macroPostOnlyApiChecks = function(url) {
	return {
		'GET': {
			topic: function() {
				var browser = newbie();
				browser.get(url, this.callback);
			},
			'should fail.': function(res, $) {
				res.should.not.have.status(200);
			}
		},
		'Empty POST': {
			topic: function() {
				var browser = newbie();
				browser.post(url, this.callback);
			},
			'should fail.': function(res, $) {
				res.should.not.have.status(200);
			}
		}
	};
};

var macroCreateUserOk = function(suite) {
	return {
		'Create user': {
			topic: function() {
				var browser = newbie();
				var data = { signupUsername: '', };
				
				data = JSON.stringify(data);
				browser.post('/api/user/create', data, this.callback);
			},
			'should succeed.': function(res, $) {
				res.should.have.status(200);
				console.log(res);
				
				// Pass created user credentials back to
				// the calling suite for later use.
				if (suite) {
				}
			}
		}
	};
};

// -------------------------------------------------------------
// User API Test Suite
//
// Run me with: vows api.user.create.vows.js --spec
// -------------------------------------------------------------

var suite = vows.describe('User API Test Suite');

// Batches  are executed sequentially.
// Contexts are executed in parallel.

suite.addBatch(macroPostOnlyApiChecks(API));
suite.addBatch(macroCreateUserOk());

suite.export(module);

var HOST = 'localhost';

var PORT = 80;

var API = "/api/user/create";

var tobi = require('tobi'),

vows = require('vows'),

assert = require('assert');

var newbie = function() { return tobi.createBrowser(PORT, HOST) };

// -------------------------------------------------------------

// Macros.

// -------------------------------------------------------------

var macroPostOnlyApiChecks = function(url) {

return {

'GET': {

topic: function() {

var browser = newbie();

browser.get(url, this.callback);

'should fail.': function(res, $) {

res.should.not.have.status(200);

}

'Empty POST': {

topic: function() {

var browser = newbie();

browser.post(url, this.callback);

'should fail.': function(res, $) {

res.should.not.have.status(200);

}

};

var macroCreateUserOk = function(suite) {

return {

'Create user': {

topic: function() {

var browser = newbie();

var data = { signupUsername: '', };

data = JSON.stringify(data);

browser.post('/api/user/create', data, this.callback);

'should succeed.': function(res, $) {

res.should.have.status(200);

console.log(res);

// Pass created user credentials back to

// the calling suite for later use.

if (suite) {

}

};

// -------------------------------------------------------------

// User API Test Suite

// Run me with: vows api.user.create.vows.js --spec

// -------------------------------------------------------------

var suite = vows.describe('User API Test Suite');

// Batches are executed sequentially.

// Contexts are executed in parallel.

suite.addBatch(macroPostOnlyApiChecks(API));

suite.addBatch(macroCreateUserOk());

suite.export(module);

Future steps then include using the macros to help set up other tests that require a valid user, etc. Overall, this is the most straightforward solution I've yet found for the problem of testing a REST API while also faking a session.

Decorators In C

Turns out you can also do decorators in C, this came in handy for something else I had to work on recently. It’s not quite as nice, because functions aren’t first-class, but handy nonetheless.

Here’s what that looks like:

#include <stdio.h>

typedef int (* const decorableFnType)(int paramOne, int paramTwo);

int functionOne(int paramOne, int paramTwo)
{
	printf("functionOne: %d, %dn", paramOne, paramTwo);
	return 0;
}

int functionTwo(int paramOne, int paramTwo)
{
	printf("functionTwo: %d, %dn", paramOne, paramTwo);
	return 0;
}

int functionThree(int paramOne, int paramTwo)
{
	printf("functionThree: %d, %dn", paramOne, paramTwo);
	return 0;
}

int decorator(int paramOne, int paramTwo, decorableFnType originalFn)
{
	printf("decorator precondition!n");
	originalFn(paramOne, paramTwo);
	return 0;
}

int main(int argc, char **argv)
{
	printf("hello, C decorators!n");
	
	functionOne(1, 2);
	
	decorator(1, 2, functionOne);
	decorator(1, 2, functionTwo);
	decorator(1, 2, functionThree);
	
	return 0;
}

#include <stdio.h>

typedef int (* const decorableFnType)(int paramOne, int paramTwo);

int functionOne(int paramOne, int paramTwo)

{

printf("functionOne: %d, %dn", paramOne, paramTwo);

return 0;

}

int functionTwo(int paramOne, int paramTwo)

{

printf("functionTwo: %d, %dn", paramOne, paramTwo);

return 0;

}

int functionThree(int paramOne, int paramTwo)

{

printf("functionThree: %d, %dn", paramOne, paramTwo);

return 0;

}

int decorator(int paramOne, int paramTwo, decorableFnType originalFn)

{

printf("decorator precondition!n");

originalFn(paramOne, paramTwo);

return 0;

}

int main(int argc, char **argv)

{

printf("hello, C decorators!n");

functionOne(1, 2);

decorator(1, 2, functionOne);

decorator(1, 2, functionTwo);

decorator(1, 2, functionThree);

return 0;

}

The output of which is:

vilimpoc@funky:~$ ./c-decorators
hello, C decorators!
functionOne: 1, 2
decorator precondition!
functionOne: 1, 2
decorator precondition!
functionTwo: 1, 2
decorator precondition!
functionThree: 1, 2
vilimpoc@funky:~$

This might be a bit simplistic, in reality, you’d probably want to decorate a function with a signature like the following, so that you can just change the structure and not bother w/a bajillion function declarations:

typedef int (* const decorableFnType)(SomeStruct * data);

1	typedef int (* const decorableFnType)(SomeStruct * data);

Again, not super elegant, but handy.

Javascript Decorators

One reason why Javascript rocks:

As a use case, imagine you want to restrict a certain set of functions to only run if you are logged in. Doing stuff like this is ridiculously easy with first-class functions.

Here’s a generic decoration example:

(function()
{
	var original = function(paramOne, paramTwo) {
		console.log('original: ' + paramOne + ' ' + paramTwo);
	};

	var decorator = function(originalFn) {
		return function(paramOne, paramTwo) {
			console.log('decorator: ' + paramOne + ' ' + paramTwo);
			originalFn(paramOne, paramTwo);
		};
	};

	var fnTable = {};
	var registerCallback = function(url, callback) {
		fnTable[url] = callback;
	};

	registerCallback('/abc', original);
	registerCallback('/def', decorator(original));

	fnTable['/abc']('one', 'two');
	fnTable['/def']('three', 'four');
})();

(function()

{

var original = function(paramOne, paramTwo) {

console.log('original: ' + paramOne + ' ' + paramTwo);

};

var decorator = function(originalFn) {

return function(paramOne, paramTwo) {

console.log('decorator: ' + paramOne + ' ' + paramTwo);

originalFn(paramOne, paramTwo);

};

var fnTable = {};

var registerCallback = function(url, callback) {

fnTable[url] = callback;

};

registerCallback('/abc', original);

registerCallback('/def', decorator(original));

fnTable['/abc']('one', 'two');

fnTable['/def']('three', 'four');

})();

Update: Here’s the specific way you’d do this with node.js/Express:

Since all of the URL handlers you register have the same signature, it’s easy to add precondition checks to the handlers via decorators.

var decorator = function(originalFn) {
    return function(req, res) {
        if (req.session.userLoggedIn) {
            originalFn(req, res);
        } else {
            redirectSomewhere(res);
        }
    }
}

app.get('/url', decorator(original));
app.post('/other', decorator(original));

var decorator = function(originalFn) {

return function(req, res) {

if (req.session.userLoggedIn) {

originalFn(req, res);

} else {

redirectSomewhere(res);

}

app.get('/url', decorator(original));

app.post('/other', decorator(original));

You get preconditions essentially for free, which is a damn sight better than adding the if() block to each and every handler function. Also, if you need more preconditions in the future, you can just stack them.

Starting Copies of Firefox with Different Profiles on Ubuntu

Just a quick note to self, how to setup Firefox to a) start separate instances of itself, b) load a different profile, c) use a particular locale.

Useful when developing localized web apps.

Repke Spaetzlerei: A Great Lunch Place

Stopped by one of my favorite spots for lunch today: Repke Spätzlerei, a cozy, cafeteria-style restaurant by Savignyplatz in Berlin.

It’s pretty busy at lunch time, as they have good deals for comfort foods like Spätzle, Schnitzel, meatloaf (Hacksteak), and Königsburger Klopse (€6,90!). The portions are a good size, but aren’t so large that they’ll put you to sleep at your next meeting. There’s always a good selection of freshly made salad sides such as: mixed bean salad, fennel and cabbage salad, or potato salad. Additionally, each of the lunch menu items usually comes with a mixed salad of some sort, with your choice of vinaigrette or yogurt dressing.

p.s. Don’t mind the crappy photos, that’s what I get for using a Motorola Milestone to take them.

Directions

Repke Spätzlerei
Bleibtreustrasse 46
10623 Berlin

Opening Hours

Daily from 11:30h