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Svelte with Test-Driven Development

You're reading from   Svelte with Test-Driven Development Advance your skills and write effective automated tests with Vitest, Playwright, and Cucumber.js

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Product type Paperback
Published in Jun 2023
Publisher Packt
ISBN-13 9781837638338
Length 250 pages
Edition 1st Edition
Languages
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Author (1):
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Daniel Irvine Daniel Irvine
Author Profile Icon Daniel Irvine
Daniel Irvine
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Table of Contents (22) Chapters Close

Preface 1. Part 1: Learning the TDD Cycle
2. Chapter 1: Setting up for Testing FREE CHAPTER 3. Chapter 2: Introducing the Red-Green-Refactor Workflow 4. Chapter 3: Loading Data into a Route 5. Chapter 4: Saving Form Data 6. Chapter 5: Validating Form Data 7. Chapter 6: Editing Form Data 8. Part 2: Refactoring Tests and Application Code
9. Chapter 7: Tidying up Test Suites 10. Chapter 8: Creating Matchers to Simplify Tests 11. Chapter 9: Extracting Logic Out of the Framework 12. Chapter 10: Test-Driving API Endpoints 13. Chapter 11: Replacing Behavior with a Side-By-Side Implementation 14. Chapter 12: Using Component Mocks to Clarify Tests 15. Chapter 13: Adding Cucumber Tests 16. Part 3: Testing SvelteKit Features
17. Chapter 14: Testing Authentication 18. Chapter 15: Test-Driving Svelte Stores 19. Chapter 16: Test-Driving Service Workers 20. Index 21. Other Books You May Enjoy

Using hand-rolled component stubs

In this section, we’ll look at a simple but effective way of mocking components, by building hand-rolled component stubs. This isn’t as clever as using a component mock library, but it’s simpler and easier to understand. Often, the simplest approach is the best choice.

To recap what we’re trying to do: we have a child component that we want to avoid rendering, perhaps because it has mount behavior or it’s a complex third-party component.

Hand-rolled component stubs rely on Vitest’s vi.mock function combined with a special __mocks__ directory. You create a stub component with the same name as your component, but inside a __mocks__ directory at the same level as the component itself. Then, you instruct Vitest to use the mock using the vi.mock statement placed at the top of your test file. This will mean the entire test suite uses the mock.

We can demonstrate this using the page route component test suite...

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