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canvas-lms/doc/testing_javascript.md

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Testing JavaScript

The process of testing JavaScript sometimes confuses people. This document's goal is to alleviate that confusion and establish how to run JavaScript tests.

With Docker and headless Chrome

This is probably the easiest way to run tests, especially for developers that don't work with Canvas on a regular basis.

Create a .env file in the repository root, containing:

COMPOSE_FILE=docker-compose.yml:docker-compose.override.yml:docker-compose/js-tests.override.yml

Then run:

docker-compose run --rm js-tests

With Docker and Webpack

This is becoming the go to standard for running Canvas and compiling your not-JavaScript (CoffeeScript, JSX, Handlebars, etc.) code into JavaScript code. You should likely be following this path when doing front-end development on Canvas. If you need help getting started with that please see development_with_docker.md and working_with_webpack.md.

Before we can get started in earnest, we need to make a few changes to a couple of files. Inside your .env file, add the phantomjs-tests override in your COMPOSE_FILE definition: docker-compose/js-phantomjs-tests.override.yml

JSpec

The jspec npm script allows you to build and run specific JavaScript specs as follows:

  1. yarn run jspec path/to/specs This will build the specified specs using webpack and run them locally using Chrome.

You can specify a directory or a single spec file to build and run. If no path is provided, all javascript specs are built and ran.

  1. yarn run jspec-watch path/to/specs This will get webpack building the specified specs in watch mode, making it so your changes are instantly (or close to instantly) reflected in the test bundle.

You can specify a directory or a single spec file to watch and build. If no path is provided, all javascript specs are watched and built.

Using jspec in this way assumes you will run the specs yourself using PhantomJS (see below) or by using yarn test to run them locally in Chrome.

PhantomJS

To run javascript specs using PhantomJS you can do so as follow:

  1. yarn run jspec-watch path/to/specs This will get webpack building the test bundle in watch mode, making it so your changes are instantly (or close to instantly) reflected in the test bundle.

    You can specify a directory or a single spec file to watch and build. If no path is provided, all javascript specs are watched and built.

  2. docker-compose run --rm phantomjs-tests This will start the PhantomJS container in watch mode running the test bundle anytime the test bundle gets updated.

So you'll now see PhantomJS almost instantly complete the test suite for you. Unfortunately, you'll also see some failures :(. Don't worry though! The reason you see failures is the lack of full support for some browser standards in PhantomJS. We don't polyfill for PhantomJS (at least when this is being written) so you'll generally see a few failures there.

Now navigate in your browser to http://phantom.docker and your tests will run inside the browser you have open (in addition to PhantomJS). This will give you the chance to debug them as well as see how they work in a fully functional browser. Our JS specs currently run in Chrome so make sure that your tests pass there.

Javascript Test Coverage

You can generate code coverage locally by having webpack set up( touch config/WEBPACK) then running COVERAGE=1 yarn test. You should then have a folder in your root directory called coverage-js in which contains an index.html which if you open it will show you the test coverage for all javascript (js, coffee, jsx)