author: Krasimir Tsonev

Hi there, I'm . Senior front-end engineer with over 13 years of experience. I write, speak and occasionally code stuff.

Extending Jasmine (BDD framework for testing)

Don't get me wrong, Jasmine is a wonderful framework. I'm using it for testing JavaScript in both places - front-end (in browser) and back-end (Nodejs). However, the client side has some disadvantages, which I just fixed. I hope that someday these changes will be moved to the official version (or at least I'll make a pull request very soon).

Controlling the rendering. I.e. patching the HtmlReporter.

Here is the typical initialization code for a test suite, which uses Jasmine.

var jasmineEnv = jasmine.getEnv();
var htmlReporter = new jasmine.HtmlReporter();
jasmineEnv.updateInterval = 1000;
jasmineEnv.addReporter(htmlReporter);
jasmineEnv.specFilter = function(spec) {
    return htmlReporter.specFilter(spec);
};
window.onload = function() {
    jasmineEnv.execute();
}

The framework generates nice markup showing the results of the tests. It works like a charm, but I can't tell to Jasmine where exactly to place the output. After a short digging in the source code I found the following lines:

jasmine.HtmlReporter = function(_doc) {
    ...
    doc.body.appendChild(dom.reporter);
    ...
}

So, it seems that I can pass something to the constructor of HtmlReporter, but it should have a property body which is actually a DOM element. I.e. I have to pass a document object. What I did is editing of jasmine-html.js on two places:

// jasmine.HtmlReporter = function(_doc) {
jasmine.HtmlReporter = function(_doc, renderIn) {

And

// doc.body.appendChild(dom.reporter);
(renderIn || doc.body).appendChild(dom.reporter);

So, now I'm able to do the following:

var htmlReporter = new jasmine.HtmlReporter(null, document.getElementById(id));

And the results are send to the right place. I.e. my own custom div holder.

Clearing HtmlReporters

Jasmine offers adding multiple reporters, which is kinda cool. The problem is that there is no method for removing them. Here is my scenario:

  • I have a function which initialize the test suite.
  • The function could be called several times and every time should start a new suite.
  • I'm using the above solution and I'm rendering the output in a custom divs
  • However var jasmineEnv = jasmine.getEnv(); actually returns same object which has already added reporters
  • From time to time I'm removing the div holders, but there are HtmlReporters attached to them
  • At the end there is an error throwing, because the divs are missing

I needed a change in jasmine.js and to be more specific in jasmine.Env.prototype. So, I added:

jasmine.Env.prototype.clearReporters = function(reporter) {
    this.reporter.clear();
};

And of course the clear method of the reporter which is actually an instance of jasmine.MultiReporter:

jasmine.MultiReporter.prototype.clear = function(reporter) {
    this.subReporters_ = [];
};

I called the method simply with:

var htmlReporter = new jasmine.HtmlReporter(null, document.getElementById(id));
jasmineEnv.clearReporters();

The support of asynchronous operations

That's actually the most important change for me. Based on the documentation you are able to test asynchronous operations like that:

it("should support async execution of test preparation and exepectations", function() {
    runs(function() {
        flag = false;
        value = 0;
        setTimeout(function() {
            flag = true;
        }, 500);
    });
    waitsFor(function() {
        value++;
        return flag;
    }, "The Value should be incremented", 750);
    runs(function() {
        expect(value).toBeGreaterThan(0);
    });
})

Too complex, don't you think. In the NodeJS version of the framework the things are much much better:

var request = require('request');
it("should respond with hello world", function(done) {
    request("http://localhost:3000/hello", function(error, response, body){
        expect(body).toEqual("hello world");
        done();
    });
});

I.e. you are receiving a function done, which you can call indicating that the test is finished. I wanted such functionality in the client side too. I managed to do this with a little change in jasmine.js. Find the following piece of code:

jasmine.Block.prototype.execute = function(onComplete) {
    if (!jasmine.CATCH_EXCEPTIONS) {
        this.func.apply(this.spec);
    }
    else {
        try {
            this.func.apply(this.spec);
        } catch (e) {
            this.spec.fail(e);
        }
    }
    onComplete();
};

And change it to:

jasmine.Block.prototype.execute = function(onComplete) {
    if (!jasmine.CATCH_EXCEPTIONS) {
        this.func.apply(this.spec, [function() {
            onComplete();
        }]);
    }
    else {
        try {
            this.func.apply(this.spec, [function() {
                onComplete();
            }]);
        } catch (e) {
            this.spec.fail(e);
        }
    }
};

I.e. I found that onComplete function actually calls the next test. Instead of executing this method directly I'm wrapping it into a function, which acts as done.

And now, I'm able to run:

it("should get the current date", function(done) {
    getCurrentDate(function(res) {
        expect(res.monthName).toBeDefined();
        done();
    });
});

P.S. My changes are based on jasmine-1.3.1 version.

If you enjoy this post, share it on Twitter, Facebook or LinkedIn. Or maybe comment below: