Advanced Angular Testing: End-to-End Testing

Aphinya Dechalert -

The art of crafting efficient, maintainable, and bug-free applications is not solely based on writing good code. It also heavily relies on our ability to ensure that everything works as expected in real-world scenarios. While unit tests provide us with an understanding of individual pieces of our application, end-to-end (E2E) tests offer insights into how everything comes together, mimicking the interactions of real users. Within the Angular ecosystem, we are endowed with tools and practices that make E2E testing intuitive and effective. This tutorial will guide you through the intricacies of setting up and conducting E2E tests for your Angular applications, leveraging tools like Protractor to achieve comprehensive and reliable testing results.

Learning Outcomes

By the end of this tutorial, you will:

  1. Understand the critical importance and the underlying mechanisms of end-to-end testing in the Angular framework.
  2. Create effective end-to-end tests that emulate user interactions and validate the overall functionality of your Angular application.
  3. Harness the power of tools like Protractor, making your testing processes streamlined, automated, and resilient against potential flaws.

Prerequisites

Before diving into this tutorial, readers should have:

  • A solid grasp of Angular and its foundational concepts.
  • Experience with basic Angular testing methodologies.
  • Familiarity with TypeScript and the Angular CLI.
  • An Angular application or project to which you can apply the techniques learned.

The Essence of End-to-End Testing

Understanding the scope and goals of E2E testing

End-to-End (E2E) testing is a methodology used to test whether the flow of an application is performing as designed from start to finish. The purpose of carrying out end-to-end tests is to identify system dependencies and to ensure that the right information is passed between various system components and systems.

The goal of E2E testing is to simulate real user scenarios, thereby validating the system under test and its components for integration and data integrity. It’s conducted from start to finish under real-world scenarios, including communication of the application with hardware, network, database, and other applications.

Differences between unit testing, integration testing, and E2E testing

Unit Testing: This is a level of software testing where individual units or components of a software are tested. The purpose is to validate that each unit of the software code performs as expected. A unit is the smallest testable part of any software.

Integration Testing: This level of testing focuses on the interfaces between units, to ensure that units work together when integrated. It aims to expose faults in the interaction between integrated units.

End-to-End Testing: This form of testing focuses on a complete application environment in a scenario that mimics real-world use, such as interacting with a database, network, hardware, or other applications. It goes beyond integration testing by also validating against real-world scenarios.

The role of E2E testing in the software development lifecycle

E2E testing plays a crucial role in the software development lifecycle (SDLC). It’s typically performed after functional and system testing and is done to replicate real user scenarios.

In SDLC, E2E testing helps validate that an application’s flow from start to finish works as expected and verifies that it integrates well with external interfaces. Thus, it helps ensure that all integrated pieces of an application work together as expected and improves confidence in its reliability.

Setting the Foundation: Angular Testing Tools

Brief introduction to Angular’s built-in testing utilities

Angular provides a robust testing framework that helps developers ensure their applications work as expected. It includes tools for both unit testing and end-to-end (E2E) testing.

For unit testing, Angular provides Karma, a test runner that spawns a web server that executes source code against test code for each given test. Along with Karma, Angular uses Jasmine, a behavior-driven development framework for testing JavaScript code. It does not depend on any other JavaScript frameworks.

Introduction to Protractor: Angular’s E2E testing framework

For E2E testing, Angular provides Protractor, an open-source E2E test framework specifically designed for Angular and built on top of WebDriverJS. Protractor runs tests against your application running in a real browser, interacting with it as a user would.

Protractor supports behavior-driven development frameworks like Jasmine or Mocha, making the testing process easier and more efficient. It also takes advantage of the specific features in Angular, such as understanding the AngularJS digest cycle, to run tests more accurately.

Here’s an example of how you might write an E2E test with Protractor:

describe('Protractor Demo App', function() {
  it('should have a title', function() {
    browser.get('http://juliemr.github.io/protractor-demo/');
    expect(browser.getTitle()).toEqual('Super Calculator');
  });
});

In this example, browser.get navigates to the URL of your application, and expect(browser.getTitle()).toEqual('Super Calculator') checks that the title of the page is ‘Super Calculator’. This is a simple example, but Protractor allows you to write more complex tests to cover all aspects of your application.

Configuring Your Angular Application for E2E Testing

Setting up Protractor and Webdriver