Jest Coverage in VS Code

Hey there! 👋 Are you looking to supercharge your Jest testing workflow in VS Code? With the right setup, you can easily visualize test coverage and streamline test runs without compromising editor performance. Here’s a simple guide to help you get started!

Step 1: Install the Jest Extension

First, install the Jest extension to bring seamless testing into your VS Code environment:

Name: Jest

ID: Orta.vscode-jest

Description: Use Facebook's Jest With Pleasure.

Version: 6.2.5

Publisher: Orta

Click here to install it!

This extension provides live feedback on your tests and highlights coverage directly in the editor.

Step 2: Configure Jest Coverage in VS Code

Now, let’s set up your settings.json file for a better visualization of test coverage:


"jest.coverageColors": {
    "covered": "#B2E0B2",           // Green for fully covered lines
    "uncovered": "#E06C75",         // Red for lines without coverage
    "partially-covered": "#D19A66"  // Yellow for partially covered lines
},
"jest.runMode": {
    "type": "on-save",
    "testFileOnly": true,
    "coverage": true},

What These Settings Do:

Red: Marks lines that are not covered, so you know where tests are missing.

Yellow: Highlights partially covered lines, pointing to areas that need better test scenarios.

Green: Lines with full coverage are not emphasized, keeping the focus on improvements.

Why You Should Try This Setup

Instant Visual Feedback: The color-coded coverage helps you quickly spot gaps in your tests, guiding you to write additional test cases and improve code reliability.

Enhanced Performance: With jest.runMode set to on-save, only the saved test file is executed. This prevents VS Code from slowing down due to unnecessary test reruns, keeping your workflow smooth and efficient.

Step 3: Explore Additional Run Modes

Want to customize your Jest experience even further? Check out the official Jest Run Mode Documentation for options:

watch: Automatically triggers tests using watchman.

on-demand: Allows you to run tests manually through the UI.

on-save: Runs tests every time you save a file. (My favorite for productivity!)

By setting up Jest in VS Code this way, you’ll be able to focus on what matters: writing high-quality, well-tested code. Happy coding, and let’s make testing effortless! 🚀