Add a test (#77)

* Match Prettier style

This way, people who have Prettier as their default formatter in their Editor (probably the majority of people) will not have the code re-formatted to double quotes if they are saving

* Add trailing-comma option

* Instruct .vscode to use ESLint as a default formatter

* Discard changes to package.json

* Add a first test

* Setup CI

* Rename to test

* move tsconfig hacks to local tsconfig.json

* Better test title

* rename file

* Fix ts setup

package.json

@@ -27,6 +27,7 @@
     "build": "./build.sh",
     "watch": "tsx scripts/bundle.ts --watch",
     "lint": "eslint .",
+    "test": "vitest --run",
     "check": "tsc -p src --noEmit && tsc -p packages/mp3-encoder/src --noEmit && tsc -p scripts --noEmit && tsc -p tsconfig.vite.json --noEmit && rm tsconfig.vite.tsbuildinfo",
     "check-docblocks": "tsx scripts/check-docblocks.ts dist/mediabunny.d.ts",
     "docs:dev": "vitepress dev docs",
@@ -80,7 +81,8 @@
     "vite": "^6.3.5",
     "vitepress": "^1.6.3",
     "vitepress-plugin-llms": "^1.5.1",
-    "vitepress-plugin-mermaid": "^2.0.17"
+    "vitepress-plugin-mermaid": "^2.0.17",
+    "vitest": "3.2.4"
   },
   "keywords": [
     "media",