0.0.5 • Public • Published


When refactoring/altering hbs files it is very easy to leave css that is no longer used or remove the css but leave the class. This addon generates a report that then details these classes. This can then gated as part of your CI to ensure that all new code is not leaving unused css, see gating below.

Note: This is not css code coverage, just "class" coverage.

This addon finds classes that do not appear in your tests and warns you that they should be addressed in some way. It generates a report ./class-coverage/report.json which will look something like:

  "classesWithNoStyles": [ ".class-1", ".class-2" ],
  "unusedStyledClasses": [  ".class-3", ".class-4"]

This shows you the classesWithNoStyles (i.e. classes that appeared in your tests but do not appear in your .css files) and the unusedStyledClasses (i.e. the classes that appear in your .css files but are never rendered to the screen during your tests). Obviously this addon is only as good as your test suite, but can be used to improve your tests.


ember install ember-cli-dead-class-finder

You now need to register the CSS classes that appear during your tests. In order to do this you will need to call the registerCssClasses method before your acceptance and integration tests:

import { module, test } from 'qunit';
import { setupApplicationTest } from 'ember-qunit';
import registerCssClasses from 'ember-cli-dead-css-finder/test-support';

module('Acceptance | Acceptance test', function(hooks) {

  test('A test', function() {


This is long and boring so there is a codemod here which you can use to do this for you.

Changing every single acceptance & integration test file is really annoying in these situations using this pattern for both acceptance and integration tests can help avoid this in the future, or you can just run the codemod. Your choice.


Once you have added the registerCssClasses as above the coverage will only be generated when the FIND_DEAD_CLASSES enrvironment variable is set to true. The running either FIND_DEAD_CLASSES=true ember s or FIND_DEAD_CLASSES=true ember test will generate the coverage report in ./class-coverage/report.json.

Ideally you should aim for this report to be empty, either by removing classes (in css/hbs files) or by adding tests to ensure that all your classes are rendered to the screen (and extra points for visual regression testing these).

Ideally you should not have any classes that are not styled however it's not always practical to test all cases, for example when including third party libraries. You can configure ember-cli-dead-class-finder in the following ways:

// ember-cli-build.js
const app = new EmberApp(defaults, {
  'ember-cli-dead-class-finder': {
  // You can specify the css files you wish to process here
    filesToProcess: ['some-file.css'], 
  // RegEx patterns of classes to ignore
    ignore: [

ember-exam support?


ember-mocha support?



This addon exposes a new command:

ember class-coverage-gate --ususedClasses=0 --stylelessClasses=0

these parameters both default to zero but can be customized to suit your use case. You can also pass the path to the report file in through --reportPath. This errors if the number of classes found is above the thresholds set.

Create a passthrough when intercepting all ajax requests in tests

To work, this addon has to post coverage results back to a middleware at /write-class-coverage.

If you are using ember-cli-mirage you should add the following:

// in mirage/config.js

  this.namespace = 'api';  // It's important that the passthrough for coverage is before the namespace, otherwise it will be prefixed.

If you are using ember-cli-pretender you should add the following:

// where ever you set up the Pretender Server

  var server = new Pretender(function () {
    this.post('/write-class-coverage', this.passthrough);


This addon was inspired by ember-cli-code-coverage.



  • git clone <repository-url>
  • cd ember-cli-dead-class-finder
  • npm install


  • npm run lint:js
  • npm run lint:js -- --fix

Running tests

  • ember test – Runs the test suite on the current Ember version
  • ember test --server – Runs the test suite in "watch mode"
  • ember try:each – Runs the test suite against multiple Ember versions

Running the dummy application

For more information on using ember-cli, visit https://ember-cli.com/.


This project is licensed under the MIT License.



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npm i ember-cli-dead-class-finder

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