Unit testing Google Closure applications from the command line

I've been playing around with building an application using Google Closure. I tried searching for a good way to run the unit tests from the command line as part of an Ant build, but either there wasn't anything out there to do what I wanted to do or I just couldn't find it.
As an aside, naming a language after a programming construct is really dumb. If you try searching for blog posts on Google Closure, you get a bunch of stuff about javascript and closures since they're such an important language concept. I think Prototype might have been a more successful language if they hadn't named themselves after a language construct as well, though the framework itself has its issues.
I'm used to writing code using test driven development, which doesn't work particularly well writing some Javascript. DOM-related code in particular is difficult to write with TDD. But there are parts of Javascript applications that can and should be well unit tested. When coding in PHP or Python, I normally have two terminal windows open for my Vim sessions and one for my build and source code management activities. I'll typically save the file I'm working on and them immediately alt-tab to the build window and hit up then enter to run my unit test target. I really wanted to do that with Javascript.

At my job we use jQuery. This comes with Qunit which is easy to run automagically with PhantomJS. But Qunit didn't look like it would be easy to make work with Closure in that it wouldn't handle the dependencies for me. And I might as well use the unit test framework for the library that I'm working with. I had a few goals. I didn't want my Javascript tests to fire up a browser. That kind of thing should be handled by Selenium. I wanted to be able to add new tests without having to manually add the test name to any file. I wanted the output to be at least somewhat pretty and clean, particularly if there were no failures. As a PHP developer I'm used to the PHPUnit output:

I decided to try to code up my own test runner to make this work. Here's the first version:

First, the build target concatenates all of the test files. In my case, test files are in a directory called tests and each of them ends with Test.js.

Next, it fires up the Closure Compiler. In this example, we've got a Javascript file called foo.js. We compile that with the concatenated test file (tests-concat.js) and the test runner (we'll get to that soon). The compiler creates a file called tests.js. We run that with phantomjs. The build will look something like this:

Most of the magic happens in testRunner.js:

Basically how it works is to override some methods in goog.testing.TestCase to capture the results. We don't particularly care about successes, so they're replaced by dots. Failures show as an F and any errors are explained in more detail after all tests finish.

I've uploaded all of the example code to Github at https://github.com/omnicolor/Closure-CLI-test-runner.

1 comment:

  1. Looks really awesome. Thanks. Any way to make it work without calcdeps.py, since that script is now deprecated? Thanks, again!