If you're going to write an insanely fast, headless test tool, how can you not call it Zombie? Zombie it is.
Zombie.js is a lightweight framefork for testing client-side JavaScript code in a simulated environment. No browser required.
Let's try to sign up to a page and see what happens:
var zombie = require("zombie");
// Load the page from localhost
zombie.visit("http://localhost:3000/", function (err, browser) {
// Fill email, password and submit form
browser.
fill("email", "zombie@underworld.dead").
fill("password", "eat-the-living").
pressButton("Sign Me Up!", function(err, browser) {
// Form submitted, new page loaded.
assert.equal(browser.text("title"), "Welcome To Brains Depot");
})
});
Well, that was easy.
To start off we're going to need a browser. A browser maintains state across requests: history, cookies, HTML 5 local and session stroage. A browser has a main window, and typically a document loaded into that window.
You can create a new zombie.Browser and point it at a document, either
by setting the location property or calling its visit function. As
a shortcut, you can just call the zombie.visit function with a URL and
callback.
The browser will load the document and if the document includes any scripts, also load and execute these scripts. It will then process some events, for example, anything your scripts do on page load. All of that, just like a real browser, happens asynchronously.
To wait for the page to fully load and all events to fire, you pass
visit a callback function. This function takes two arguments. If
everything is successful (page loaded, events run), the callback is
called with null and a reference to the browser. If anything went
wrong (page not loaded, event errors), the callback is called with an
error.
If you worked with Node.js before you're familiar with this callback pattern. Every time you see a callback in the Zombie.js API, it works that way: the first argument is an error, or null if there is no error, with interesting value in the second argument.
Typically the second argument would be a reference to the browser or window object you called. This may seem redudant, but works suprisingly well when composing with other asynchronous APIs, for example, when using Zombie.js with Vows.
Whenever you want to wait for all events to be processed, just call
browser.wait with a callback.
There are several ways you can inspect the contents of a document. For starters, there's the DOM API, which you can use to find elements and traverse the document tree.
You can also use CSS selectors to pick a specific element or node list.
Zombie.js implements the DOM Selector
API. These functions are
available from every element, the document, and the Browser object
itself.
To get the HTML contents of an element, read its innerHTML property.
If you want to include the element itself with its attributes, read the
element's outerHTML property instead. Alternatively, you can call the
browser.html function with a CSS selector and optional context
element. If the function selects multiple elements, it will return the
combined HTML of them all.
To see the textual contents of an element, read its textContent
property. Alternatively, you can call the browser.text function with
a CSS selector and optional context element. If the function selects
multiple elements, it will return the combined text contents of them
all.
Here are a few examples for checking the contents of a document:
// Make sure we have an element with the ID brains.
assert.ok(browser.querySelector("#brains"));
// Make sure body has two elements with the class hand.
assert.equal(browser.body.querySelectorAll(".hand").length, 2);
// Check the document title.
assert.equal(browser.text("title"), "The Living Dead");
// Show me the document contents.
console.log(browser.html());
// Show me the contents of the parts table:
console.log(browser.html("table.parts"));
CSS selectors are implemented by Sizzle.js. In addition to CSS 3
selectors you get additional and quite useful extensions, such as
:not(selector), [NAME!=VALUE], :contains(TEXT), :first/:last and
so forth. Check out the Sizzle.js
documentation for more details.
You're going to want to perform some actions, like clicking links, entering text, submitting forms. You can certainly do that using the DOM API, or several of the convenience functions we're going to cover next.
To click a link on the page, use clickLink with selector and callback.
The first argument can be a CSS selector (see Hunting) or the text
contents of the A element you want to click. The second argument is a
callback, which is passed on to browser.wait (see Walking). In
other words, it gets fired after all events are processed, with error
and browser as arguments.
Let's see that in action:
// Now go to the shopping cart page and check that we have
// three bodies there.
browser.clickLink("View Cart", function(err, browser) {
assert.equal(browser.querySelectorAll("#cart .body"), 3);
});
To submit a form, use pressButton. The first argument can be a CSS
selector, the button name (the value of the name argument) or the text
that shows on the button. You can press any BUTTON element or INPUT
of type submit, reset or button. The second argument is a
callback, just like clickLink.
Of course, before submitting a form, you'll need to fill it with values.
For text fields, use the fill function, which takes two arguments:
selector and the field value. This time the selector can be a CSS
selector, the field name (its name attribute), or the text that shows
on the label associated with that field.
Zombie.js supports text fields, password fields, text areas, and also the new HTML 5 fields types like email, search and url.
The fill function returns a reference to the browser, so you can chain
several functions together. Its sibling functions check and uncheck
(for check boxes), choose (for radio buttons) and select (for drop
downs) work the same way.
Let's combine all of that into one example:
// Fill in the form and submit.
browser.
fill("Your Name", "Arm Biter").
fill("Profession", "Living dead").
select("Born", "1968")
uncheck("Send me the newsletter").
pressButton("Sign me up", function(err, browser) {
// Make sure we got redirected to thank you page.
assert.equal(browser.location, "http://localhost:3003/thankyou");
});
Shortcut for creating new browser and calling browser.visit on it.
Returns the body Element of the current document.
Checks a checkbox.
Selects a radio box option.
Clicks on a link. Clicking on a link can trigger other events, load new page, etc: use a callback to be notified of completion. Finds link by text content or selector.
The current system clock according to the browser (see also browser.now).
Returns all the cookies for this domain/path. Path defaults to "/".
Returns the main window's document. Only valid after opening a document (see browser.open).
Fill in a field: input field or text area.
Fire a DOM event. You can use this to simulate a DOM event, e.g. clicking a
link. These events will bubble up and can be cancelled. With a callback, this
function will call wait.
Returns the HTML contents of the selected elements.
Returns the last error received by this browser in lieu of response.
Returns the last request sent by this browser.
Returns the last response received by this browser.
Returns local Storage based on the document origin (hostname/port).
Return the location of the current document (same as window.location.href).
Changes document location, loads new document if necessary (same as setting
window.location).
The current system time according to the browser (see also browser.clock).
Open new browser window.
Press a button (button element or input of type submit). Typically this will
submit the form. Use the callback to wait for the from submission, page to
load and all events run their course.
Select a single element (first match) and return it.
Select multiple elements and return a static node list.
Selects an option.
Returns session Storage based on the document origin (hostname/port).
Returns the text contents of the selected elements.
Unchecks a checkbox.
Loads document from the specified URL, processes events and calls the callback.
Process all events from the queue. This includes resource loading, XHR requests, timeout and interval timers. Calls the callback when done.
The terminator is optional and can be one of:
null, missing -- process all events- Number -- process that number of events
- Function -- called after each event, returns false to stop processing
Returns the main window.
function (browser) { }
Emitted whenever the event queue goes back to empty.
function (browser) { }
Emitted whenever new page loaded. This event is emitted before DOMContentLoaded.
function (error) { }
Emitted if an error occurred loading a page or submitting a form.
Zombie.js is written in CoffeeScript, a language that mixes the best parts of Python and Ruby and compiles one-to-one into JavaScript.
To get started hacking on Zombie.js you'll need Node.js, NPM and CoffeeScript:
$ brew install node npm
$ npm install coffee-script
Next, install all other development and runtime dependencies:
$ cake setup
The DOM implementation is JSDOM, which provides
pretty decent emulation of DOM Level 3. There are some issues and some
features Zombie.js needs but JSDOM doesn't care for (e.g default event
handlers). Those are patched onto JSDOM in
lib/zombie/jsdom_patches.coffee and lib/zombie/forms.coffee.
DOM selectors are provided by Sizzle.js, and
vendored in the vendor directory.
Zombie.js is tested using Vows. Since we're
testing a Web browser, we also need a Web server, so it spins up an
instance of Express. Spinning up Express and
making sure it doesn't power down before all tests are done (Vows is
asynchronous, like everything in Node) is the responsibility of
spec/helper.coffee.
To run the test suite:
$ vows
To stress Zombie.js, we have test cases that use Sammy.js and jQuery.
The scripts themselves are contained in the spec/.scripts directory.
The dot is necessary to hide these JS files from Vows.
Zombie.js documentation is written in Markdown.
Everything you need to know to get started is covered by README.md, so
it shows up when you visit the Github
page.
Additional documentation lives in the doc directory. Annotated source
code generated using Docco.
To generate the documentation
$ cake doc
$ open html/index.html
- Find assaf/zombie on Github
- Fork the project
- Add tests
- Make your changes
- Send a pull request
Check out the outstanding to-dos.
Zombie.js is copyright of Assaf Arkin, released under the MIT License.
Zombie.js is written in CoffeeScript for Node.js.
Sizzle.js is copyright of John Resig, released under the MIT, BSD and GPL.