VSCode Textmate Grammar Test Runner

vscode-tmgrammar-test is a utility for testing VSCode TextMate grammars using a user-friendly plaintext file format, inspired by Sublime Text's syntax testing capabilities. The package provides both unit and snapshot testing functionalities, allowing developers to verify syntax highlighting behavior against a VSCode engine. The current stable version is v0.1.3, with releases occurring periodically to introduce new features, fix bugs, and address breaking changes, such as the removal of certain CLI options and dropping Node.js 10.x support in v0.1.1. Key differentiators include its direct use of the VSCode TextMate engine for accurate simulation, a clear and concise assertion syntax within test files for precise scope checking, and built-in snapshot testing for tracking grammar changes over time. It is designed to be integrated as a development dependency, primarily invoked via its command-line interface, making it an essential tool for grammar authors.