ember-test-selectors

Enabling better element selectors in Ember.js tests

Features

• Removes attributes starting with data-test- from HTML tags and component/helper invocations in your templates for production builds

• Removes properties starting with data-test- from your JS objects like component classes for production builds

• Automatically binds properties starting with data-test- on all components for development/testing builds

More information on why that is useful are available on our blog!

Compatibility

• Ember 2.16 or above
• Ember CLI 2.14 or above
• Node.js 8 or above

Installation

ember install ember-test-selectors

Usage

In your templates you are now able to use data-test-* attributes, which are automatically removed from production builds:

<article>
  <h1 data-test-post-title data-test-resource-id="{{post.id}}">{{post.title}}</h1>
  <p>{{post.body}}</p>
</article>

Once you've done that you can use attribute selectors to look up the elements:

// in Acceptance Tests:

find('[data-test-post-title]')
find('[data-test-resource-id="2"]')

// in Component Integration Tests:

this.$('[data-test-post-title]').click()
this.$('[data-test-resource-id="2"]').click()

Usage in Components

You can also use data-test-* attributes on components:

{{comments-list data-test-comments-for=post.id}}

These data-test-* attributes will be bound automatically and available as data attributes on the <div> wrapping the component template:

<div id="ember123" data-test-comments-for="42">
  <!-- comments -->
</div>

You can also use boolean attributes, but make sure it is the first parameter as this makes use of Ember's positional params system.

{{! valid }}
{{comments-list data-test-comments post=post}}

{{! compiler error }}
{{comments-list post=post data-test-comments}}

Usage in Computed Properties

Instead of assigning data-test-comment-id in this example template:

{{#each comments as |comment|}}
  {{comment-list-item comment=comment data-test-comment-id=comment.id}}
{{/each}}

you may also use computed properties on the component:

export default Ember.Component({
  comment: null,
  'data-test-comment-id': Ember.computed.readOnly('comment.id'),
});

As with data-test-* attributes in the templates, these properties, whether computed or not, will be removed automatically in production builds.

Usage with tagless components

Since tagless components do not have a root element, data-test-* attributes passed to them cannot be bound to the DOM. If you try to pass a data-test-* attribute to a tagless component, or define one in its Javascript class, ember-test-selectors will throw an assertion error.

However, there are some cases where you might want to pass a data-test-* attribute to a tagless component, for example a tagless wrapper component:

// comment-wrapper.js
export default Ember.Component({
  tagName: ''
})

{{!-- comment-wrapper.hbs --}}
Comment:
{{comment-list-item comment=comment data-test-comment-id=data-test-comment-id}}

{{!-- comment-list.hbs --}}
{{#each comments as |comment|}}
  {{comment-wrapper comment=comment data-test-comment-id=comment.id}}
{{/each}}

In this case, to prevent the assertion on the specific comment-wrapper component, you can specify supportsDataTestProperties on the class:

// comment-wrapper.js
export default Ember.Component({
  tagName: '',
  supportsDataTestProperties: true
})

supportsDataTestProperties, like data-test-* properties, will be stripped from the build.

Configuration

You can override when the data-test-* attributes should be stripped from the build by modifying your ember-cli-build.js file:

var app = new EmberApp({
  'ember-test-selectors': {
    strip: false
  }
});

strip accepts a Boolean value and defaults to !app.tests, which means that the attributes will be stripped for production builds, unless the build was triggered by ember test. That means that if you use ember test --environment=production the test selectors will still work, but for ember build -prod they will be stripped out.

Deprecations

The testSelector helper was deprecated in v0.3.7. There's a codemod available at https://github.com/lorcan/test-selectors-codemod that can help make the necessary transformations to address the deprecation.

License

ember-test-selectors is developed by and © simplabs GmbH and contributors. It is released under the MIT License.

ember-test-selectors is not an official part of Ember.js and is not maintained by the Ember.js Core Team.