Angular End-to-End Testing

Angular E2E testing involves testing the entire application as a whole, including multiple components, services, and interactions between different parts of the application. It tests the complete end-to-end flow and ensures that all components work together correctly by writing an end to end test.

End-to-End (E2E) testing in Angular involves testing the entire application workflow from start to finish to ensure that everything works together as expected. Angular provides robust tools and frameworks for E2E testing, with Protractor traditionally being the most popular choice.

However, Protractor has been deprecated, and many developers are now using Cypress for E2E testing in Angular applications. This guide will cover setting up and writing E2E tests in Angular using Cypress.

Even though testing is not a common consensus amongst programmers, it is for sure an imperative strategy. Test Driven Development (TDD) and Behavior Driven Development (BDD) are the most used approaches; BDD was created from TDD. For testing the smallest unit of code, we use unit testing; for testing the system working, we use e2e tests.

For creating e2e tests in Angular.

Running end-to-end (E2E) tests in Angular typically involves testing the entire application flow, including user interactions, navigation, and data validation. The best approach to run E2E tests in Angular involves selecting the right testing framework, setting up a robust testing environment, and structuring your tests effectively. Here’s a step-by-step guide:

Choose a Testing Framework

Angular developers often use Protractor or Cypress for E2E testing. These are popular testing frameworks known for their widespread adoption and relevance in the testing community. Each has its own strengths and weaknesses:

Protractor

This is the official E2E testing framework for Angular. It’s based on WebDriverJS and works well with Angular applications out of the box. Protractor was developed by the Angular team, ensuring its stability and benefits for testing Angular apps. However, it’s considered somewhat outdated compared to newer tools like Cypress.

Cypress

Cypress is a modern, developer-friendly E2E testing framework. It’s known for its ease of use, fast test execution, and rich debugging capabilities. While Cypress tests are highly regarded for their simplicity and speed, Protractor tests are often used in Angular projects to create and run test cases using configuration and spec files. Cypress is a popular choice for Angular projects and is suitable for both small and large applications.

Comparing E2E Testing Frameworks: Protractor vs. Cypress

Feature	Protractor	Cypress
Purpose	Designed specifically for Angular applications	General purpose E2E testing framework
Installation	More complex setup, requires Selenium and WebDriver	Simple installation with `npm install cypress`
Integration with Angular	Built for Angular, integrates seamlessly	Can be integrated with any front-end framework, including Angular
Speed	Slower due to WebDriver communication	Faster, runs directly in the browser
Debugging	More challenging, involves multiple processes	Excellent debugging tools with real-time reload
Community Support	Extensive, but declining due to deprecation	Growing rapidly with strong community support
Learning Curve	Steeper, requires understanding of Selenium WebDriver	Lower, easier for beginners to pick up
Test Writing Syntax	Uses Jasmine or Mocha for test writing	Uses Mocha and Chai for test writing
Real-time Reloading	No real-time reloading	Supports real-time reloading
Automatic Waiting	Requires manual handling of waits and timeouts	Automatic waiting for DOM elements to be available
Parallel Testing	Supported through Selenium Grid	Built-in parallelization support
Screenshots and Videos	Requires additional setup	Automatically captures screenshots and videos
Browser Support	Supports multiple browsers through WebDriver	Supports Chrome and Firefox, with limited support for others
CI Integration	Supported, but requires more configuration	Seamless CI integration with many providers
Custom Commands	Limited and complex to implement	Easy to create custom commands
API Testing	Not natively supported	Built-in support for API testing

2. Set Up Your Testing Environment:

Regardless of the testing framework you choose, you’ll need to set up your testing environment:

Install Node.js and npm if you haven’t already. — Create a separate Angular project for your E2E tests or integrate them into your existing Angular project. — Install the chosen testing framework (Protractor or Cypress) and any required dependencies. — Configure your testing framework and write a configuration file for your E2E tests. This may involve specifying the base URL of your Angular application and other settings. — Create and organize your test files. Ensure they are structured and named according to the conventions of the testing framework you are using.

3. Write E2E Tests:

Create E2E tests to cover different user scenarios and application functionalities. Your tests should interact with your application as a user would:

Simulate user actions like clicking buttons, filling out forms, and navigating between pages.
Assert that the application behaves as expected, checking for correct data display, error messages, and other UI elements.

Organize your tests into meaningful suites and spec files to keep them maintainable. The spec file is the actual test file where assertions are located and verified.

4. Handle Authentication:

If your Angular application requires user authentication, ensure that your E2E tests can handle it. You may need to create test users or use tokens to authenticate in your tests.

5. Mock Backend Services:

To isolate your E2E tests from external dependencies and ensure consistent testing, consider mocking backend services. Use tools like ng-mocks, Angular’s HttpClientTestingModule, or interceptors to stub API calls and responses.

6. Run Your Tests:

Execute your E2E tests using the testing framework’s command-line tools or integrations with CI/CD pipelines. Run your tests locally during development and in your CI/CD pipeline to catch regressions early.

Remember that E2E tests are an essential part of ensuring the quality and reliability of your Angular application. Regularly review and update your testing strategy to accommodate changes in your application’s architecture and requirements.

In end-to-end testing, you mimic that user’s actions, activities, and the experience of a real user using the application. Create test suites to group related tests together, making it easier to manage and maintain your tests. Below is a list of a few best practices to get the best out of end-to-end testing.

Test Repeated User scenarios

End-to-end testing is very complex and requires time to test out all the possible edge cases completely. Avoid testing every possible edge case and focus only on the most common and important scenarios.

Prioritize the Right Aspects

It's important to prioritize what you're testing because it can easily become cumbersome and complex. Therefore, it's important to prioritize business-impacted features before going over other less important edge cases.

Make Testing Realistic

Sometimes, you want to make end-to-end testing a little realistic. In most cases, real users stop by to look at images or pause and watch a few videos before moving on with their actions. End-to-end testing should mirror real-life interactions as much as possible.

Error Monitoring

End-to-end testing is a very complex process because it encompasses the walkthrough of the whole application or sometimes only the features that were newly added. However, the complexity can be reduced by ensuring many errors are resolved during coding before end-to-end testing.

Optimize Testing Environment

You can facilitate the testing process by creating an optimum test environment. Creating an optimum test environment allows for minimal setup when it's time to test and clear out data for your next test.

How to Set up Cypress

1. Setting Up Cypress in Angular

First, you need to install Cypress in your Angular project.

Install Cypress:
```
bash
npm install cypress --save-dev
```

Add Cypress to scripts in package.json:


json
"scripts": { "cypress:open": "cypress open", "cypress:run": "cypress run" }

Initialize Cypress Configuration: Open Cypress for the first time to create the necessary configuration files.
```
bash
npm run cypress:open
```

This will create a cypress folder with the following structure:


cypress ├── fixtures ├── integration ├── plugins └── support cypress.json

2. Configuring Cypress

Modify cypress.json to set up your base URL and other configurations:


json
{ "baseUrl": "http://localhost:4200", "integrationFolder": "cypress/integration", "fixturesFolder": "cypress/fixtures", "pluginsFile": "cypress/plugins/index.js", "supportFile": "cypress/support/index.js" }

3. Writing Your First E2E Test

Create a test file in the cypress/integration folder, e.g., home.spec.js:


/* javascript */
describe('Home Page', () => {
  it('should display the welcome message', () => {
    cy.visit('/');
    cy.contains('Welcome to Your Angular App').should('be.visible');
  });
});

4. Running E2E Tests

Run tests in the Cypress Test Runner:
```
bash
npm run cypress:open
```
This opens the Cypress Test Runner where you can interactively run and debug your tests.
Run tests in headless mode:
```
bash
npm run cypress:run
```

5. Writing More Complex Tests

Example: Testing a Form Submission

Create a form component in Angular:


<!-- form.component.html -->
<form (ngSubmit)="onSubmit()" #form="ngForm">
  <input type="text" ngModel name="username" required>
  <button type="submit">Submit</button>
</form>

Create a test file for the form:


/* javascript */
describe('Form Page', () => {
  beforeEach(() => {
    cy.visit('/form');
  });
  it('should submit the form successfully', () => {
    cy.get('input[name="username"]').type('testuser');
    cy.get('button[type="submit"]').click();
    cy.contains('Form submitted successfully!').should('be.visible');
  });
  it('should show validation error if username is empty', () => {
    cy.get('button[type="submit"]').click();
    cy.contains('Username is required').should('be.visible');
  });
});

6. Integrating with Continuous Integration (CI)

To integrate Cypress tests with your CI pipeline, add the following to your CI configuration file (e.g., GitHub Actions, GitLab CI, Travis CI):

Example: GitHub Actions Workflow


# yaml
name: CI
on: [push, pull_request]
jobs:
  e2e-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Set up Node.js
        uses: actions/setup-node@v2
        with:
          node-version: '14'
      - run: npm install
      - run: npm run start &
        continue-on-error: true
      - run: npx wait-on http://localhost:4200
      - run: npm run cypress:run

Benefits of End to End Testing

Reduced Risks

With this deployment workflow mostly in place, any stage release of the application will be tested. Any issues with a specific functionality ought to have been found sooner.

Increased Confidence

Real user actions were taken into account when these tests were carried out while considering actual user activities. We would be more confident in making our release public if an issue were found early on.

Reduced Cost and Time

Pushing a buggy application into production doesn't demonstrate a positive user experience. And to fix the bug, we might need to apply a fix and set aside time for debugging. Having this additional layer of e2e testing security might cost us a lot of money and effort.

Selecting the right testing framework and structuring it seems like a challenge?
Angular Minds, an Angular development company can help you select the most suitable testing framework, set up the environment, and structure the tests effectively.

Future Trends in E2E Testing for Angular Applications

As the landscape of web development continues to evolve, so do the trends in E2E testing for Angular applications. One significant trend is the shift towards more developer-friendly frameworks like Cypress, which offer superior speed, ease of use, and powerful debugging capabilities. This shift is driven by the need for faster development cycles and more efficient testing processes.

Additionally, there is a growing emphasis on integrating E2E testing into Continuous Integration/Continuous Deployment (CI/CD) pipelines to ensure that tests are run automatically with every code change, enhancing the reliability and robustness of Angular applications.

The use of AI and machine learning to identify and predict potential issues before they occur is also gaining traction, enabling more proactive testing strategies. Furthermore, the adoption of Progressive Web Apps (PWAs) and their unique testing requirements is pushing the development of more specialized E2E testing tools and practices.

Lastly, the trend towards more holistic testing approaches that combine E2E testing with other types of testing, such as unit and integration testing, is becoming increasingly popular, providing a comprehensive validation of application functionality and performance.

These trends highlight the ongoing evolution of E2E testing in keeping pace with the demands of modern web development.

Conclusion

End-to-end testing emphasizes more functional flow.
It can help to find out issues before public release.
Protractor, Cypress, Playwright, etc. tools can be used for e2e testing

E2E testing is a crucial part of ensuring the reliability and functionality of your Angular application. By using Cypress, you can write comprehensive tests that simulate real user interactions, providing confidence that your application behaves as expected. Setting up Cypress is straightforward, and its powerful features make it an excellent choice for modern E2E testing.