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

Extracting Logic Out of the Framework

An important property of maintainable software is its testability. This is the idea that all parts of the application should be straightforward to test. More specifically, the design of the application code should make it easy to write automated unit tests.

In this chapter, we’ll look at one technique for improving testability: moving domain logic out of the framework and into plain JavaScript. Plain JavaScript code is simpler to test because there are no complex framework objects that interact with your code.

The following diagram shows how to think about a SvelteKit code base in this way.

Figure 9.1 – Keeping application code outside of framework components to aid testability

Figure 9.1 – Keeping application code outside of framework components to aid testability

In Chapter 7, Tidying up Test Suites, we took a step toward moving the storage of birthday data items into a birthdayRepository module. We’ll continue that process by pushing data validation out of the SvelteKit form...