Testing Ember.js Components: A Beginner's Guide

When I was learning component testing in the ember.js, I was multiple things were started in that doc, it has various parts and numerous modules that need to be learned to write those test cases. I agree that you don’t need to learn all of that to write test cases, but these are some topics that we should know, and here is the curated list of all the resources as well.

Key Concepts

1. Ember-test-helpers

This package helps to make the testing experience good in the emberjs applications it provides multiple functions like, onclick() , fillIn(), routing and rendering helpers (visit(), render(), ...) and some other things that make it easy to write good tests.

ember-test-helpers

2. QUnit

Qunit is the default testing framework for Ember.js. It provides assertions like assert.ok(), assert.equal(), and assert.deepEqual() to validate test results.

• Example:

    import { module, test } from 'qunit';
  
    module('Basic Ember Test', function() {
      test('truthy test', function(assert) {
        assert.ok(true, 'This test will always pass');
      });
    });
  

• Resource: QUnit Docs , Qunt Dom

3. Module Setup (module, hooks.beforeEach())

The module function groups related tests together, and hooks.beforeEach() sets up state before each test runs.

• Example:

    module('Component | my-component', function(hooks) {
      hooks.beforeEach(function() {
        // set up state
      });
  
      test('it renders', function(assert) {
        assert.ok(true);
      });
    });
  

4. Rendering Components (render())

The render() function from @ember/test-helpers is used to mount a component in a test.

• Example:

    import { render } from '@ember/test-helpers';
    import { hbs } from 'ember-cli-htmlbars';
  
    test('it renders a message', async function(assert) {
      await render(hbs`<MyComponent @message="Hello" />`);
      assert.dom('p').hasText('Hello');
    });
  

• Resource: Ember Test Helpers

5. Assertions (assert.dom())

Assertions help verify DOM changes. @ember/test-helpers provides assert.dom() for querying elements.

• Example:

    assert.dom('button').exists();
    assert.dom('h1').hasText('Welcome');
  

• Resource: @ember/test-helpers API

6. Actions and Events (click(), fillIn())

You can simulate user interactions using helpers like click() and fillIn().

• Example:

    import { click, fillIn } from '@ember/test-helpers';
  
    test('it updates input', async function(assert) {
      await fillIn('input', 'New Value');
      await click('button');
      assert.dom('p').hasText('New Value');
    });
  

Conclusion

Ember.js provides a rich testing ecosystem with QUnit, @ember/test-helpers, and ember-qunit. By mastering module(), render(), and user event helpers like click(), you can write solid component tests.

For further reading:

• https://guides.emberjs.com/release/testing/testing-components/