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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:

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.

For a hands-on experience, run tests and explore the test code in your browser as your read this guide.

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.

Jasmine HTML Reporter in the browser

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

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

Step 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 dash (--) is needed to pass arguments into the npm script.

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

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

Configure project for Travis CI

Step 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.

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

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

Configure project for GitLab CI

Step 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.

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

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

Configure project for GitHub Actions

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

Step 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

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

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

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.

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Licensed under the Creative Commons Attribution License 4.0.
https://v12.angular.io/guide/testing