AVA vs Jest: What are the differences?

Introduction

In this article, we will discuss the key differences between AVA and Jest, two popular testing frameworks used for JavaScript applications. AVA and Jest offer similar functionalities but have some distinct features that set them apart.

1. Test Execution: AVA runs tests in parallel by default, using separate Node.js processes for each test file. This allows for faster test execution, as multiple test files can be executed simultaneously. On the other hand, Jest runs tests serially by default, executing them one after the other. While this may result in slower test execution, it can be advantageous for debugging and isolating test failures.

2. Configuration: AVA has a more minimalistic approach to configuration compared to Jest. It requires a minimal configuration to get started, making it easier to set up and use. Jest, on the other hand, provides a more extensive and flexible configuration system, allowing developers to customize various aspects of the testing environment.

3. Mocking: Jest has built-in mocking capabilities, making it easier to create and manage mock modules, functions, and dependencies. It provides a simple API for creating mocks and allows for advanced mocking techniques such as mock functions and timers. AVA, on the other hand, does not have built-in mocking capabilities but can leverage external libraries for mocking if needed.

4. Snapshot Testing: Jest includes snapshot testing functionality, which allows developers to capture and compare snapshots of rendered components. This provides an easy way to track changes in the component's output and detect unintended changes. AVA does not have built-in snapshot testing functionality, but developers can use external libraries or custom solutions for snapshot testing.

5. Watch Mode: Jest provides a watch mode that automatically detects changes in source or test files and re-runs the affected tests. This is particularly useful during development, as it allows for quick iteration and feedback on code changes. AVA does not have a built-in watch mode but can be integrated with tools like nodemon to achieve similar functionality.

6. Additional Features: Jest offers additional features such as code coverage reporting, built-in code transformers (like Babel and TypeScript), built-in matchers for assertions, and support for parallel test execution in a single process. AVA, on the other hand, focuses more on simplicity and minimalism, and does not provide these additional features out of the box.

In summary, AVA and Jest are both powerful testing frameworks for JavaScript applications, but they have some key differences. AVA emphasizes parallel test execution, minimalistic configuration, and simplicity, while Jest offers features like mocking, snapshot testing, extensive configuration, and other additional functionalities. The choice between AVA and Jest ultimately depends on the specific requirements and preferences of the development team.