Code coverage for ember apps using Istanbul
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lifeart and rwwagner90 TypeScript integration (howto) (#196)
* TypeScript integration (howto)

* removed some abstraction

* 1.0.0-beta.6
Latest commit 5987f6c Sep 21, 2018

ember-cli-code-coverage npm version Build Status

Code coverage using Istanbul for Ember apps.


  • If using Mocha, Testem >= 1.6.0 for which you need ember-cli > 2.4.3
  • If using Mirage you need ember-cli-mirage >= 0.1.13
  • If using Pretender (even as a dependency of Mirage) you need pretender >= 0.11.0
  • If using Mirage or Pretender, you need to set up a passthrough for coverage to be written.
  • ember-cli-babel >= 6.0.0


  • ember install ember-cli-code-coverage


Coverage will only be generated when an environment variable is true (by default COVERAGE) and running your test command like normal.

For example:

COVERAGE=true ember test

If you want your coverage to work on both Unix and Windows, you can do this:

npm install cross-env --save-dev

and then:

cross-env COVERAGE=true ember test

When running with parallel set to true, the final reports can be merged by using ember coverage-merge. The final merged output will be stored in the coverageFolder.

TypeScript integration


  • in tsconfig.json
    "compilerOptions": {
      "inlineSourceMap": true,
      "inlineSources": true
  • in ember-cli-build.js
  const app = new EmberApp(defaults, {
    babel: {
      sourceMaps: 'inline'
    sourcemaps: {
      enabled: true,
      extensions: ['js']
  • in package.json specify latest available version
    devDependencies: {
      "ember-cli-code-coverage": "^1.0.0-beta.6"


Configuration is optional. It should be put in a file at config/coverage.js (configPath configuration in package.json is honored). In addition to this you can configure Istanbul by adding a .istanbul.yml file to the root directory of your app (See


  • coverageEnvVar: Defaults to COVERAGE. This is the environment variable that when set will cause coverage metrics to be generated.

  • reporters: Defaults to ['lcov', 'html']. The json-summary reporter will be added to anything set here, it is required. This can be any reporters supported by Istanbul.

  • excludes: Defaults to ['*/mirage/**/*']. An array of globs to exclude from instrumentation. Useful to exclude files from coverage statistics.

  • coverageFolder: Defaults to coverage. A folder relative to the root of your project to store coverage results.

  • parallel: Defaults to false. Should be set to true if parallel testing is being used for separate test runs, for example when using ember-exam with the --partition flag. This will generate the coverage reports in directories suffixed with _<random_string> to avoid overwriting other threads reports. These reports can be joined by using the ember coverage-merge command (potentially as part of the posttest hook in your package.json).


  module.exports = {
    coverageEnvVar: 'COV'

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-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 () {'/write-coverage', this.passthrough);


This addon was inspired by ember-cli-blanket. The primary differences are that this addon uses Istanbul rather than Blanket for coverage and it instruments your application code as part of the build, when enabled.