Testing

Testing your Angular application helps you check that your app is working as you expect.

Prerequisites

Before writing tests for your Angular app, you should have a basic understanding of the following concepts:

• Angular fundamentals
• JavaScript
• HTML
• CSS
• Angular CLI

The testing documentation offers tips and techniques for unit and integration testing Angular applications through a sample application created with the Angular CLI. This sample application is much like the one in the Tour of Heroes tutorial.

If you'd like to experiment with the application that this guide describes, run it in your browser or download and run it locally.

Set up testing

The Angular CLI downloads and installs everything you need to test an Angular application with the Jasmine test framework.

The project you create with the CLI is immediately ready to test. Just run the ng test CLI command:

ng test

The ng test command builds the application in watch mode, and launches the Karma test runner.

The console output looks a bit like this:

10% building modules 1/1 modules 0 active
…INFO [karma]: Karma v1.7.1 server started at http://0.0.0.0:9876/
…INFO [launcher]: Launching browser Chrome …
…INFO [launcher]: Starting browser Chrome
…INFO [Chrome …]: Connected on socket …
Chrome …: Executed 3 of 3 SUCCESS (0.135 secs / 0.205 secs)

The last line of the log is the most important. It shows that Karma ran three tests that all passed.

A Chrome browser also opens and displays the test output in the "Jasmine HTML Reporter" like this.

Most people find this browser output easier to read than the console log. Click on a test row to re-run just that test or click on a description to re-run the tests in the selected test group ("test suite").

Meanwhile, the ng test command is watching for changes.

To see this in action, make a small change to app.component.ts and save. The tests run again, the browser refreshes, and the new test results appear.

Configuration

The CLI takes care of Jasmine and Karma configuration for you.

Fine-tune many options by editing the karma.conf.js in the root folder of the project and the test.ts files in the src/ folder.

The karma.conf.js file is a partial Karma configuration file. The CLI constructs the full runtime configuration in memory, based on application structure specified in the angular.json file, supplemented by karma.conf.js.

Search the web for more details about Jasmine and Karma configuration.

Other test frameworks

You can also unit test an Angular application with other testing libraries and test runners. Each library and runner has its own distinctive installation procedures, configuration, and syntax.

Search the web to learn more.

Test file name and location

Look inside the src/app folder.

The CLI generated a test file for the AppComponent named app.component.spec.ts.

The test file extension must be .spec.ts so that tooling can identify it as a file with tests (also known as a spec file).

The app.component.ts and app.component.spec.ts files are siblings in the same folder. The root file names (app.component) are the same for both files.

Adopt these two conventions in your own projects for every kind of test file.

Place your spec file next to the file it tests

It's a good idea to put unit test spec files in the same folder as the application source code files that they test:

• Such tests are painless to find
• You see at a glance if a part of your application lacks tests
• Nearby tests can reveal how a part works in context
• When you move the source (inevitable), you remember to move the test
• When you rename the source file (inevitable), you remember to rename the test file

Place your spec files in a test folder

Application integration specs can test the interactions of multiple parts spread across folders and modules. They don't really belong to any part in particular, so they don't have a natural home next to any one file.

It's often better to create an appropriate folder for them in the tests directory.

Of course specs that test the test helpers belong in the test folder, next to their corresponding helper files.

Set up continuous integration

One of the best ways to keep your project bug-free is through a test suite, but you might forget to run tests all the time. Continuous integration (CI) servers let you set up your project repository so that your tests run on every commit and pull request.

There are paid CI services like Circle CI and Travis CI, and you can also host your own for free using Jenkins and others. Although Circle CI and Travis CI are paid services, they are provided free for open source projects. You can create a public project on GitHub and add these services without paying. Contributions to the Angular repository are automatically run through a whole suite of Circle CI tests.

This article explains how to configure your project to run Circle CI and Travis CI, and also update your test configuration to be able to run tests in the Chrome browser in either environment.

Configure project for Circle CI

1. Create a folder called .circleci at the project root.

2. In the new folder, create a file called config.yml with the following content:

   version: 2
   jobs:
     build:
       working_directory: ~/my-project
       docker:
         ‐ image: circleci/node:10-browsers
       steps:
         ‐ checkout
         ‐ restore_cache:
             key: my-project-{{ .Branch }}-{{ checksum "package-lock.json" }}
         ‐ run: npm install
         ‐ save_cache:
             key: my-project-{{ .Branch }}-{{ checksum "package-lock.json" }}
             paths:
               ‐ "node_modules"
         ‐ run: npm run test -- --no-watch --no-progress --browsers=ChromeHeadlessCI

   This configuration caches node_modules/ and uses npm run to run CLI commands, because @angular/cli is not installed globally. The double hyphen (--) characters is needed to pass arguments into the npm script.

3. Commit your changes and push them to your repository.

4. Sign up for Circle CI and add your project. Your project should start building.

   • Learn more about Circle CI from Circle CI documentation.

Configure project for Travis CI

1. Create a file called .travis.yml at the project root, with the following content:

   language: node_js
   node_js:
     ‐ "10"
   
   addons:
     chrome: stable
   
   cache:
     directories:
        ‐ ./node_modules
   
   install:
     ‐ npm install
   
   script:
     ‐ npm run test -- --no-watch --no-progress --browsers=ChromeHeadlessCI

   This does the same things as the CircleCI configuration, except that Travis doesn't come with Chrome, so use Chromium instead.

2. Commit your changes and push them to your repository.

3. Sign up for Travis CI and add your project. You'll need to push a new commit to trigger a build.

   • Learn more about Travis CI testing from Travis CI documentation.

Configure project for GitLab CI

1. Create a file called .gitlab-ci.yml at the project root, with the following content:

   image: node:14.15-stretch
   variables:
     FF_USE_FASTZIP: "true"
   
   cache:
     untracked: true
     policy: push
     key: ${CI_COMMIT_SHORT_SHA}
     paths:
       ‐ node_modules/
   
   .pull_cached_node_modules:
     cache:
       untracked: true
       key: ${CI_COMMIT_SHORT_SHA}
       policy: pull
   
   stages:
     ‐ setup
     ‐ test
   
   install:
     stage: setup
     script:
       ‐ npm ci
   
   test:
     stage: test
     extends: .pull_cached_node_modules
     before_script:
       ‐ apt-get update
       ‐ wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
       ‐ apt install -y ./google-chrome*.deb;
       ‐ export CHROME_BIN=/usr/bin/google-chrome
     script:
       ‐ npm run test -- --no-watch --no-progress --browsers=ChromeHeadlessCI

   This configuration caches node_modules/ in the install job and re-uses the cached node_modules/ in the test job.

2. Sign up for GitLab CI and add your project. You'll need to push a new commit to trigger a build.

3. Commit your changes and push them to your repository.

   • Learn more about GitLab CI testing from GitLab CI/CD documentation.

Configure project for GitHub Actions

1. Create a folder called .github/workflows at root of your project.

2. In the new folder, create a file called main.yml with the following content:

   name: CI Angular app through Github Actions
   on: push
   jobs:
     build:
       runs-on: ubuntu-latest
       steps:
         ‐ uses: actions/checkout@v2
         ‐ name: Use Node.js 14.x
           uses: actions/setup-node@v1
           with:
             node-version: 14.x
   
         ‐ name: Setup
           run: npm ci
   
         ‐ name: Test
           run: |
             npm test -- --no-watch --no-progress --browsers=ChromeHeadlessCI

3. Sign up for GitHub and add your project. You'll need to push a new commit to trigger a build.

4. Commit your changes and push them to your repository.

   • Learn more about GitHub Actions from GitHub Actions documentation

Configure CLI for CI testing in Chrome

While the CLI command ng test is generally running the CI tests in your environment, you might still need to adjust your configuration to run the Chrome browser tests.

There is a configuration file for the Karma JavaScript test runner, which you must adjust to start Chrome without sandboxing.

We'll be using Headless Chrome in these examples.

• In the Karma configuration file, karma.conf.js, add a custom launcher called ChromeHeadlessCI below browsers:

  browsers: ['ChromeHeadlessCI'],
  customLaunchers: {
    ChromeHeadlessCI: {
      base: 'ChromeHeadless',
      flags: ['--no-sandbox']
    }
  },

Now, run the following command to use the --no-sandbox flag:

ng test --no-watch --no-progress --browsers=ChromeHeadlessCI

NOTE: Right now, you'll also want to include the --disable-gpu flag if you're running on Windows. See crbug.com/737678.

More information on testing

After you've set up your application for testing, you might find the following testing guides useful.

	Details
Code coverage	How much of your app your tests are covering and how to specify required amounts.
Testing services	How to test the services your application uses.
Basics of testing components	Basics of testing Angular components.
Component testing scenarios	Various kinds of component testing scenarios and use cases.
Testing attribute directives	How to test your attribute directives.
Testing pipes	How to test pipes.
Debugging tests	Common testing bugs.
Testing utility APIs	Angular testing features.