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

Migrating tests with a test todo list

The task at hand is moving the validation logic out of the SvelteKit form action we completed in Chapter 5, Validating Form Data, and into the birthdayRepository module. And in this section, we’ll plan that task using a new technique.

You might remember that the birthdayRepository module already exists but has no tests. That’s a situation that we often find ourselves in when we extract modules during refactoring. And it’s often perfectly okay to leave these modules untested. The issue comes when we want to modify the behavior of these modules: where do we add the tests?

There’s no clear answer to that, but in this case, we’ll use the opportunity to duplicate all the tests from the form action in the birthdayRepository module, in addition to adding some new tests too.

Deleting tests in the original location

We won’t delete the original tests, but that is something you should consider doing so...