Book Image

Svelte with Test-Driven Development

By : Daniel Irvine
Book Image

Svelte with Test-Driven Development

By: Daniel Irvine

Overview of this book

Svelte is a popular front-end framework used for its focus on performance and user-friendliness, and test-driven development (TDD) is a powerful approach that helps in creating automated tests before writing code. By combining them, you can create efficient, maintainable code for modern applications. Svelte with Test-Driven Development will help you learn effective automated testing practices to build and maintain Svelte applications. In the first part of the book, you’ll find a guided walkthrough on building a SvelteKit application using the TDD workflow. You’ll uncover the main concepts for writing effective unit test cases and practical advice for developing solid, maintainable test suites that can speed up application development while remaining effective as the application evolves. In the next part of the book, you’ll focus on refactoring and advanced test techniques, such as using component mocks and writing BDD-style tests with the Cucumber.js framework. In the final part of the book, you’ll explore how to test complex application and framework features, including authentication, Svelte stores, and service workers. By the end of this book, you’ll be well-equipped to build test-driven Svelte applications by employing theoretical and practical knowledge.
Table of Contents (22 chapters)
1
Part 1: Learning the TDD Cycle
8
Part 2: Refactoring Tests and Application Code
16
Part 3: Testing SvelteKit Features

Using page object models in Playwright tests

A page object model is simply a plain JavaScript class that groups up the mechanical actions of navigating a page (locating a field, clicking a button, or filling in a text field) into methods that describe high-level operations that occur within your application (completing a birthday form).

In this section, you’ll build a page object model named BirthdayListPage that will allow you to rewrite your existing Playwright tests more simply.

Let’s get started by adding the new class:

  1. Create a new file named tests/BirthdayListPage.js and give it the following content. It creates the basic class along with a single method, goto, which is used to navigate to the /birthdays application URL:
    export class BirthdayListPage {
      constructor(page) {
        this.page = page;
      }
      async goto() {
        await this.page.goto('/birthdays');
      }
    ...