Intro to Testing in Ember.js
Published: 2022-12-11 05:47:03

[**Ember.js**](https://emberjs.com/) is a popular JavaScript framework for building ambitious web applications. It provides a robust set of tools for testing and ensuring the reliability of your code. In this blog post, we will explore the different types of tests that you can write in Ember.js and how to set up your testing environment.

## Types of tests in Ember.js
Ember.js uses QUnit as its testing library, which provides several types of tests that you can write for your application. The most common types are:

- **Unit tests**: These tests focus on a single unit of code, such as a function or a service. They are usually small and fast, and they test the individual components of your application in isolation.

- **Integration tests**: These tests focus on the interactions between multiple components of your application. They are typically longer and more complex than unit tests, and they test how the different parts of your application work together.

- **Acceptance tests**: These tests focus on simulating the behavior of a user using your application. They are typically written in a natural language, such as English, and they test the end-to-end functionality of your application.

## Setting up the testing environment

To get started with testing in Ember.js, you will need to set up the testing environment in your project. This typically involves installing the necessary dependencies, configuring the test runner, and creating the necessary files and folders for your tests.

To install the necessary dependencies, run the following command in your terminal:

```sh
npm install --save-dev ember-qunit ember-cli-qunit
```
This will install the **ember-qunit** and **ember-cli-qunit** packages, which provide the necessary tools for running tests in Ember.js.

Next, you will need to configure the test runner by creating a **testem.js** file in the root of your project. This file should look something like this:

```js
module.exports = {
  test_page: 'tests/index.html?hidepassed',
  disable_watching: true,
  launch_in_ci: [
    'Chrome'
  ],
  launch_in_dev: [
    'Chrome'
  ]
};
```
This configuration specifies that the test runner should use the tests/index.html file as the entry point for running tests, and it should launch the tests in Chrome. You can customize this configuration to suit your specific needs.

Finally, you will need to create the necessary files and folders for your tests. In Ember.js, tests are typically organized into the following folders:

- **unit**: This folder contains unit tests for your application.
- **integration**: This folder contains integration tests for your application.
- **acceptance**: This folder contains acceptance tests for your application.

Each of these folders should contain a tests subfolder, where you will place the individual test files for your application. For example, if you want to write a unit test for a user-service service, you would create a user-service-test.js file in the unit/tests folder.

## Writing tests in Ember.js

Once you have set up your testing environment, you can start writing tests for your Ember.js application. In this section, we will go over the basics of how to write tests in Ember.js using QUnit.



The basic structure of a test in Ember.js is as follows:
```js
import { module, test } from 'qunit';

module('Unit | Service | user service', function(hooks) {
  hooks.beforeEach(function() {
    // Runs before each test in this module
  });

  hooks.afterEach(function() {
    // Runs after each test in this module
  });

  test('it exists', function(assert) {
    let service = this.owner.lookup('service:user-service');
    assert.ok(service);
  });

  test('it does something', function(assert) {
    let service = this.owner.lookup('service:user-service');
    assert.equal(service.doSomething(), 42);
  });
});

```
In this example, we are writing a unit test for a **user-service** service. We have defined two tests: **it exists** and **it does something**. The **it exists** test simply checks that the service exists and is properly registered with Ember's dependency injection system. The **it does something** test calls a method on the service and checks that it returns the expected result.

Each test consists of a call to the **test** function, which takes a description of the test and a callback function that contains the actual test code. The callback function is provided with an **assert** object, which contains a number of helper methods for making assertions about the state of your application. In the example above, we are using the **ok** and **equal** methods to make assertions about the service.

In addition to the **test** function, you can also use the **module** function to group related tests together. The **module** function takes a description of the module and a callback function that contains the setup and teardown code for the tests in the module. In the example above, we are using the **hooks.beforeEach** and **hooks.afterEach** hooks to run some code before and after each test in the module.

## Running tests in Ember.js

Once you have written some tests for your Ember.js application, you can run them using the **ember test** command. This command will launch the test runner and execute all of the tests in your application. You can specify which types of tests you want to run by using the **--filter** option, for example:
```sh
ember test --filter=unit
```
This command will only run the unit tests in your application. You can also run the tests in a specific module by using the **--module** option, for example:
```sh
ember test --filter=unit --module=user service
```
This command will only run the unit tests in the **user service** module.

Ember.js also provides a few other options for running tests, such as the ability to run the tests in watch mode or to generate a code coverage report. You can learn more about these options by running the **ember help test** command.

In conclusion, testing is an important part of building reliable and maintainable applications with Ember.js. By using the tools provided by QUnit and Ember.js, you can easily write and run tests for your application to ensure that it behaves as expected. Happy testing!