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 or Pretender, you need Pretender >= 0.11.0

• 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

Configuration is optional. It should be put in a file at config/coverage-config.js.

• 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.

Aka when using ember-cli-mirage or Pretender. You may require a version of Pretender that includes this fix.

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

// in mirage/config.js

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

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.