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

Designing a store for birthdays

The code for this chapter includes a single store in the src/stores/birthdays.js file with the following content:

import { writable } from 'svelte/store';
export const birthdays = writable([]);

The idea of the birthdays store is to store whatever birthdays have been returned from the SvelteKit page load. It’s kept up to date by the page route component.

There’s also a new NextBirthday component that reads the store and displays a message at the top of the page alerting the user to the next upcoming birthday.

Stores aren’t necessary for this change

This feature could have been written simply by passing birthdays as a prop to NextBirthday. It’s certainly worth avoiding stores if you can simply use component props. This chapter’s code is intended to be educative only; in reality I would not use a store for this use case.

Figure 15.1 – The Birthdays application with the new alert

Figure 15.1 – The Birthdays application...