LumenDiff ⚡

High-performance visual regression testing tool written in Rust.

LumenDiff drastically reduces the time spent on CI/CD visual regression pipelines by leveraging Rust's zero-cost abstractions, multi-threading, and raw memory access.

✨ Features

• Extreme Speed: Multi-threaded screenshot capture via CDP (chromiumoxide) and parallel CPU-bound image diffing using rayon.
• Seamless Integration: Compatible with existing Storybook static builds and familiar configuration structures.
• Zero-overhead Diffing: Custom raw-byte pixel comparison algorithm that skips expensive PNG decoding for unchanged components.
• Built-in Static Server: Instant local static file serving powered by axum and tokio.
• Framework Agnostic: Currently supports Storybook (v6 & v7+), with architecture ready for Ladle and Histoire.

🚀 Quick Start

1. Installation

You can install LumenDiff directly via Cargo:

cargo install lumendiff

2. Usage

Build your Storybook locally:

npm run build-storybook

Run LumenDiff in the root of your project:

lumendiff

LumenDiff will automatically read your .lumendiff.yaml (if available), spin up a static server, capture the snapshots, and compare them against your baseline.

⚙️ Configuration

LumenDiff can be configured via a .lumendiff.yaml file in the root of your project. All fields are optional and will fallback to sensible defaults.

# .lumendiff.yaml
storybookShots:
  storybookUrl: ./storybook-static
  breakpoints: 
    - 360
    - 1280
waitBeforeScreenshot: 500
concurrency: 8
threshold: 0.05

CLI Arguments

You can override configuration values directly from the terminal:

lumendiff --storybook-dir ./dist/docs --concurrency 12 --threshold 0.02

Run lumendiff --help for a full list of commands.

📁 Directory Structure

After running the tool, LumenDiff manages your visual state in the .lumendiff folder:

• .lumendiff/baseline/: The accepted source of truth for your components.
• .lumendiff/snapshots/: The latest captured screenshots.
• .lumendiff/diffs/: Highlighted diff images for components that failed the threshold.

🛣️ Roadmap

• Storybook support
• Parallel diffing & capturing
• Threshold configuration
• Support for Ladle
• Support for Histoire
• CI/CD GitHub Action