add test script

packages/remark-lsx/package.json

@@ -19,7 +19,8 @@
     "lint:js": "yarn eslint **/*.{js,jsx,ts,tsx}",
     "lint:styles": "stylelint --allow-empty-input src/**/*.scss src/**/*.css",
     "lint:typecheck": "tsc",
-    "lint": "run-p lint:*"
+    "lint": "run-p lint:*",
+    "test": "vitest run --coverage"
   },
   "// comments for dependencies": {
     "escape-string-regexp": "5.0.0 or above exports only ESM"