AtomCoverage

Add code coverage to your Atom package

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Currently only the following languages/frameworks are supported:

• Languages:
  • ES6 (ECMAScript2015)
• Testing frameworks:
  • mocha (through atom-mocha)
• Coverage frameworks:
  • nyc

Feel free (and encouraged!) to contribute and improve this package to work with other languages/frameworks!

Quickstart

$ cd your-atom-pkg
$ npm install babel-cli babel-core babel-plugin-istanbul \
  babel-preset-env nyc atom-mocha atom-coverage --save-dev
$ npm run test:coverage

After installing, you'll have two new NPM scripts (won't be overwritten if already present):

• test:coverage: runs your specs and generates code coverage reports on finish.
• check:coverage: checks if your coverage is above your thresholds. Read how to configure thresholds with nyc.

I strongly recommend you to define your tests script as cross-env NODE_ENV=test atom --test spec/*.spec.js spec/**/*.spec.js. apm test does not allow for subdirectories, as opposed to atom --test. Having subfolders allows a clearer, properly scoped structure for your tests/specs.

NOTE: atom --test spec/*.js will fail if no .js files present at spec/, and atom --test spec/**/*.js will fail if no .js files present in any subfolder under spec/. This has nothing to do with AtomMocha, but Atom itself, so define your test script congruently/coherently with your project structure.

Configuration files

atom-coverage uses the config files of the involved frameworks if present. If any of them is missing or has an incorrect configuration, it will automatically create them or solve the conflicts for you (to some extent, of course).

Assuming atom-pkg/ is the root folder of your Atom package, let's dig into each config file...

atom-pkg/.atom-coverage(.(json|yaml|yml))?

This is the configuration file for atom-coverage itself. You can also provide this configuration through the property atomCoverage inside your Atom package's package.json.

The list of currently supported options are:

Option	Type	Description	Default	Valid
instrumenter	String	The coverage framework to use	nyc	nyc
transpiler	String	The transpiler to use	babel	babel
sourcesRoot	String	The relative path to the root of your Atom package's source files	lib/ src/	-
testScript	Script	The NPM script to execute your tests and get them covered with the configured instrumenter	test	-

atom-pkg/.babelrc

This is the configuration file for babel, which atom-coverage uses to transpile your ES6 code into ES5 that nyc understands. The minimum required configuration is:

{
  "env": {
    "test": {
      "plugins": [
        // You must install as devDep any babel plugin that your Atom package
        // requires to get successfully transpiled, and include it here
        "...",
        "istanbul"
      ],
      "sourceMaps": "inline"
    }
  },
  "presets": ["env"]
}

Helpful links:

• .babelrc reference
• Babel plugins reference

NOTE 1: The order of the Babel plugins matters, so you must find the correct order for your code to get transpiled, being istanbul always the last one (AtomCoverage enforces this).

NOTE 2: atom-coverage does NOT currently support Babel config in package.json.

atom-pkg/.nycrc(.json)?

This is the configuration file for nyc, which atom-coverage uses to analyze the code coverage of your pre-instrumented files.

Some nyc options don't work when pre-instrumenting source files. You don't need to care about this, since atom-coverage fixes them for you! The list of fixed options includes (but is not limited to, since I haven't thoroughly tested all options):

• include: String[]: array of glob-compliant strings. If you provide a folder instead of a glob (i.e., lib or lib/), it will be extended to recursively get all JavaScript files in that folder (previous example would be extended to lib/**/*.js).
• all: boolean: set all=true inside your nyc config file to recursively, automagically get all your source files under sourcesRoot folder included and covered.

Helpful links:

• nyc official site
• nyc code for its settings API

NOTE: atom-coverage does NOT currently support nyc config in package.json.

testquire(uutPath: string, requireIt: boolean = true)

We will refer to you files/modules as UUT (Units Under Test) from here on.

AtomCoverage wraps your NPM test command to analyze the code coverage based on your package tests. It doesn't make any magic to infer how to test your specs. You must define that in an NPM script, given by the option testScript (which defaults to test script if not provided).

You need to require() your pre-instrumented files instead your source files inside your tests/specs for the code coverage to work, but this would break your tests when running without coverage (in that case you should only request your source files). That's why this package exports an alternative require() called testquire(), which loads your source files or the pre-instrumented ones, depending if you request code coverage (thus loading pre-instrumented files) or not (thus loading source files). You don't need to configure anything. It resolves both cases automatically for you. The only thing you need inside your tests/specs is:

const { testquire } = require('atom-coverage');
const uut = testquire('path/relative/to/sources/root/for/uut');

NOTE: You don't need to care about the depth level of your source/test files! atom-coverage automatically takes charge of that for you too!

Example

Let's assume you keep your source files under lib/, and you want to load a file placed at lib/folder1/folder2/file.js. Then you require it inside your test/spec as:

const { testquire } = require('atom-coverage');
const uut = testquire('folder1/folder2/file');

If you run npm test, testquire() will require your source file at lib/folder1/folder2/file.js.

If you run npm run test:coverage, testquire() will require your instrumented file at coverage/.instrumented/folder1/folder2/file.js (assuming that you're using the default options for nyc and atom-coverage).

Stubbing your UUT's dependencies

What if you want to stub some of your files/modules inside your instrumented files? You can do that with the awesome proxyquire package.

You need to feed proxyquire() with the path to your instrumented files to inject your stubs, but hardcoding the paths would be unmaintainable (and it would break running only your specs, in addition). That's why you can pass a second parameter requireIt to testquire(), which manages whether (1) to require the file and return it (requireIt=true) or (2) not (requireIt=false). So you could use proxyquire as follows:

const { testquire } = require('atom-coverage');
const proxyquire = require('proxyquire');
const uutPath = testquire('folder1/folder2/file', false);
const uutDepStub = {};
const uut = proxyquire(uutPath, {
  'path/to/dep/exactly/as/required/inside/uut': uutDepStub,
});

NOTE: Requiring NodeJS core modules or external dependencies is done as usual (i.e., require('fs') or require('npmPackage')).

Contributing

If you would like to contribute to projects, please, read carefully the semantic-release contributing guidelines, which I adhere to, and do the following:

# 01. Clone your fork of this repository into a local folder. 
$ git clone [e-mail]:your-user/atom-coverage.git
# 02. Enter the cloned package. 
$ cd ./atom-coverage
# 03. Assign the original repo to a remote called "upstream". 
$ git remote add upstream https://github.com/cgalvarez/atom-coverage
# 04. Create a new topic branch off the master branch that describe 
#     what your PR does and use it. 
$ git checkout -b 'your-pr-topic'
# 05. Choose on command to install the package dependencies based on 
#     your package manager. 
$ (yarn|npm) install
# 06. Make your changes and write specs to test them. 
# 07. Ensure that your changes pass the project requirements 
#     (linting, tests, coverage...). 
$ (yarn|npm) run check
# 08. Once you've finished, commit your changes with commitizen. 
$ (yarn|npm) run semantic-commit
# 09. Send a pull request describing what you have done. 

FAQ

Does/will this package support my desired testing/coverage framework?

If you want to support a different testing/coverage framework, please, help other developers with the same needs/preferences/desires as you 😊, help the open source community ❤️ and contribute to the project by making an awesome pull request! ✨

Author

© 2018 Carlos García (@cgalvarez), All rights reserved.

License

AtomCoverage is released under the MIT License.