Mocking Techniques in Vitest

What you will learn:

In this practical workshop, you will learn:

• The purpose of mocking;
• What and when to mock;
• How to write mocks that are beneficial rather than a maintenance burden;
• How to separate mocks from implementation details;
• How to ensure type safety in mocks;
• And all the mocking techniques you need to test your code!

By solving real-world tasks using the Vitest framework, you will gain a complete understanding of mocking and finally make it a useful tool in your testing arsenal.

Workshop Structure: The workshop consists of 6 blocks of exercises dedicated to different mocking techniques for various data types.

Boundaries

Understand what mocking really is and how it helps create test boundaries. Learn how each mock affects the code being tested with clear examples.

Mocking Functions

Functions are at the core of JavaScript logic. Learn to mock functions for effective testing of input and output data. Create mocks for functions, track their calls, and configure behavior in the code being tested.

Mocking Date and Time

Eliminate side effects of changing date and time in tests. Learn how to “freeze” time and mock time-dependent code to ensure stable test results.

Mocking Global Variables

Explore how to mock implicit dependencies without disruption. Learn to mock global values, methods, and environment variables, creating the perfect testing environment.

Mocking Network Requests

Gain control over network requests and reliably test client-side code. Intercept requests and mock responses using Mock Service Worker, simulating various network scenarios.

Mocking Modules

Understand when to use module mocking and explore alternative techniques. Learn to safely mock modules using Vitest's built-in APIs.

Who this workshop is for: This workshop is intended for all developers, both newcomers to automated testing and those who have been writing tests for years. If you are unsure when to introduce mocks into your test suite or how to do it without having to redo it the next day, this workshop is designed especially for you.