yiewd

Generator-based WebDriver client, wrapper around Wd.js

npm install yiewd
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Yiewd

Yiewd is a Wd.js wrapper that uses V8's new generators for cleaner code! It's called yiewd because it uses the new yield syntax with wd. yield + wd = yiewd. Amazing, right? And a great way to exercise vowel pronunciation.

Yiewd is made possible with the monocle-js library.

Install with: npm install yiewd

The problem

Let's say we want to write a webdriver test:

var wd = require('wd')
  , driver = wd.remote();

driver.init(desiredCaps, function(err, sessionId) {
  if (err) return postTest(err);
  driver.get("http://mysite.com", function(err) {
    if (err) return postTest(err);
    driver.elementById("someId", function(err, el) {
      if (err) return postTest(err);
      el.click(function(err) {
        if (err) return postTest(err);
        setTimeout(function() { // pause a bit
          driver.elementById("anotherThing", function(err, el2) {
            if (err) return postTest(err);
            el2.text(function(err, text) {
              if (err) return postTest(err);
              text.should.equal("What the text should be");
              driver.quit(postTest);
            });
          });
        }, 1500); // what's this random number doing here? It goes with the pause!
      });
    });
  });
});

Yeah, that sucks. Look at that callback pyramid! Look at all those repetitive error checks!

The (generator-based) solution

Let's all be a little more sane, shall we?

var yiewd = require('yiewd')
  , driver = yiewd.remote();

driver.run(function*() {
  var sessionId, el, el2, text;
  sessionId = yield this.init(desiredCaps);
  yield this.get("http://mysite.com");
  yield this.elementById("someId").click();
  yield this.sleep(1.5);
  text = yield this.elementById("anotherThing").text();
  text.should.equal("What the text should be");
  yield this.quit();
});

Niiice.

How it works

Basically, you get a driver object as a result of the call to wd.remote(). You can use this driver object inside a monocle o-routine to yield to asynchronous function execution rather than using callbacks. And you'll get the result of the callback as the assignment to the yield expression!

Once you have a driver object, you can use driver.run as a way to kick off a series of commands inside a generator. Here you have access to the driver object as this, so you can do things like yield this.get("http://mysite.com").

Integrating with test suites

It's relatively easy to break up bits of sessions between testcases and so on. Here's what a simple mocha test suite could look like:

var yiewd = require('yiewd');

describe('my cool feature', function() {
  var driver = null;  // driver object used across testcases

  // global setUp, tearDown
  before(function(done) {
    driver = yiewd.remote();
    driver.run(function*() {
      yield this.init(desiredCaps);
      done();
    });
  });
  after(function(done) {
    driver.run(function*() {
      yield this.quit();
      done();
    });
  });

  it('should do some thing', function(done) {
    driver.run(function*() {
      // test logic
      done();
    });
  });

  it('should do another thing', function(done) {
    driver.run(function*() {
      // test logic
      done();
    });
  });
});

Notice how you get a driver object from yiewd.remote(). You can hold onto this and later use driver.run() and pass it another generator which will take over execution for the driver. Easy!

Composing functionality

Using monocle-js, you can compose your own custom automation behaviors:

var o_O = require('monocle-js').o_O
  , yiewd = require('yiewd')
  , driver = yiewd.remote();

var flow1 = o_O(function*() {
  yield driver.get('http://mywebpage.com');
  yield driver.elementByCss('a').click();
});

var flow2 = o_O(function*() {
  yield driver.elementByCss('input[type=text]').sendKeys("my text");
  yield driver.elementById('submit').click();
});

describe('my cool feature', function() {
  it('should do some things', function(done) {
    driver.run(function*() {
      yield this.init(desiredCaps);
      yield flow1();
      yield flow2();
      yield flow1(); // reuse flow1
      done();
    });
  });
});

Chaining driver calls

Often in WebDriver-land, you only want to find an element in order to do something with it. In those cases, it's a bit tedious to do something like this:

var el1 = yield driver.elementById('someEl');
var text = yield el1.text();
text.should.equal("hello world");

Of course, using Javascript™ we can already "chain" these calls:

var text = yield (yield driver.elementById('someEl')).text();
text.should.equal("hello world");

But we have this goofy double-yield business. So Yiewd lets you do away with it:

var text = yield driver.elementById('someEl').text()
text.should.equal("hello world");

Integrating with Sauce Labs

We've got some special sauce so you can sauce while you Sauce:

var yiewd = require('yiewd')
  , driver = yiewd.sauce(userName, accessKey);

driver.run(function*() {
  yield this.init(desiredCaps);
  yield this.get('http://saucelabs.com/guinea-pig/');
  try {
    var title = yield this.title();
    title.should.include("I am a page title");
    yield this.reportPass();
  } catch (e) {
    yield this.reportFail();
  }
  yield this.quit();
});

Probably the pass/fail reporting would be handled in some kind of global tearDown method, of course.

Requirements

Either:

  • Node >= 0.11.3 (one with generators)
  • Make sure you start your test runner with the --harmony flag; this might be non-trivial but for mocha, see below.

Or:

  • Any recent node
  • Run your test scripts through regenerator to get generator support, e.g.:

      regenerator my_test.js > my_test_es5.js && mocha my_test_es5.js
    

And:

  • For running tests: npm install -g mocha

Run the Tests

Make sure you have your chromedriver-enabled Selenium server running, then:

mocha -R spec -t 60000 --harmony test/

Architecture

This is a simple wrapper around Wd.js that is really easy to maintain: (a) new methods from Wd.js can be added with one word in Yiewd, (b) there's nothing really to maintain beyond the generator glue which should stabilize quickly.

Contributing

Give it a whirl and contribute bugfixes! Pull requests welcome. Biggest area of need right now is filling out our testsuite to make sure everything works correctly.

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