nit

Author: mxschmitt

package.json

@@ -22,6 +22,7 @@
     "atest": "playwright test --config=tests/android/playwright.config.ts",
     "etest": "playwright test --config=tests/electron/playwright.config.ts",
     "webview2test": "playwright test --config=tests/webview2/playwright.config.ts",
+    "extensiontest": "playwright test --config=tests/extension/playwright.config.ts",
     "itest": "playwright test --config=tests/installation/playwright.config.ts",
     "stest": "playwright test --config=tests/stress/playwright.config.ts",
     "biditest": "playwright test --config=tests/bidi/playwright.config.ts",