debug Playwright driver

November 6, 2024

We may encounter the following errors when running Playwright tests:

If the error can be reproduce locally but no obvious issues can be identified, you can follow this article to debug the InjectedScript in the browser that drives by Playwright.

The main working principle of Playwright is to inject JavaScript code into the browser, communicate with the Node layer (test code + Playwright server driver) to drive the browser, and simulate user behavior.

We can debug the server side code like debugging a normal Node process. For the injected code in the browser, please follow the following steps:

Run Playwright tests with headless mode off and env var PWTEST_UNDER_TEST = 1
1. see playwright/packages/playwright-core/src/utils/debug.ts at d4ad520a9bf0fea78b610c065af0b0c896229666 · microsoft/playwright
In the browser that brought by playwright, open devtools / console，print & show function definition of __injectedScript.constructor
Set break point that you wishes to debug, like checkElementStates :

source: https://insider.affine.pro/workspace/af3478a2-9c9c-4d16-864d-bffa1eb10eb6/dRMIGB3bd0IdVWKFrEoBm?mode=page&blockIds=z5WJ5eHNS3mwTGpgmbzh1

debug Playwright driver

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