feat(layout): test and demo setup

[yvonneyx]

• 搭建本地开发环境
• 搭建截图测试环境

[gemini-code-assist]

Summary of Changes

Hello @yvonneyx, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on enhancing the development workflow for the layout package by setting up a modern and efficient testing and demo infrastructure. It integrates snapshot testing for visual regression, provides an interactive environment for demonstrating layout algorithms, and updates the build and development tooling to leverage Vite and a more streamlined TypeScript configuration. These changes aim to improve the quality, testability, and ease of development for future layout features.

Highlights

• Development and Testing Environment Setup: This pull request establishes a comprehensive local development and testing environment for the layout package, as indicated by the PR description: '准备本地开发与测试环境' (Prepare local development and testing environment).
• Snapshot Testing Integration: Introduced robust snapshot testing capabilities using Jest, custom matchers (toMatchSVGSnapshot), and SVG optimization (svgo) to ensure visual consistency of layout outputs. This includes utilities for creating canvas instances and managing snapshot directories.
• Interactive Demo Infrastructure: A new interactive demo system has been set up, allowing developers to visualize and test different layout algorithms. The initial demo showcases the CircularLayout with adjustable parameters via a lil-gui interface.
• Build and Development Tooling Updates: Switched the development server from Webpack to Vite for improved performance and developer experience. Jest configuration has been significantly updated to support the new testing setup, including jsdom environment, jest-canvas-mock, and path aliases.
• TypeScript Configuration Refinement: The TypeScript configuration (tsconfig.json) has been refactored to include test files, define path aliases (@, @@), and introduce a dedicated tsconfig.build.json for ESM builds, enhancing project structure and maintainability.

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[gemini-code-assist]

Code Review

本次 PR 为 layout 包搭建了测试和演示环境，引入了 Vite 用于本地开发，并配置了 Jest 进行单元测试和快照测试。整体结构清晰，为后续的开发和测试打下了良好基础。

我在代码中发现了一些可以改进的地方，主要集中在：

• 测试工具函数中的一个严重 bug，可能导致 ReferenceError。
• 快照测试工具中可能导致快照不正确的逻辑。
• 演示代码中一些可以增强类型安全性的地方。

具体的修改建议请见下面的评论。

[gemini-code-assist]

这部分代码似乎在不必要地复制 SVG 元素的内容。svg 变量已经是 canvas DOM 元素的完整克隆。通过再次克隆并将其子节点追加到 gRoot，你实际上是在 gRoot 内部复制了所有子节点。这可能会导致快照内容不正确，包含重复的元素。如果这段代码没有特殊用途，建议移除以避免潜在的快照错误。