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 a factory method for creating data objects

It’s time to simplify the Arrange phase of the tests using a factory method named createBirthday.

The last section mentioned how each of the Arrange-Act-Assert phases needs a different treatment for simplification. A key method for the Arrange phase is the use of factories. You already created one of those in Chapter 4, Saving Form Data. That was the createFormDataRequest method that you used in the preceding section.

Using test factories to hide irrelevant data

Factory methods help you generate supporting objects in the shortest amount of code possible. One way they do that is by setting default values for object properties so that you don’t need to specify them. You’re then free to override those defaults in each individual test.

Hiding necessary but irrelevant data is a key method for keeping unit tests succinct and clear.

Our birthday objects have a very simple structure, with just three fields...