Why Playwright Tests Pass Locally but Fail in CI

A Playwright test that passes on your laptop but fails in CI is not behaving randomly. It is exposing a dependency your test already had. Most teams call this “CI flakiness” too early. That label is usually too vague to be useful. What is really happening is a mix of environmental mismatch and hidden assumptions. Your laptop is already warmed up. You may already be logged in. Your machine may be faster in the ways that matter for your app. You are probably running fewer tests at once. CI removes a lot of that comfort. That is why a test can look healthy during development and still break the moment it runs inside a container, on a hosted runner, or across multiple shards. The important mindset shift is simple: CI failures are rarely random. They expose assumptions your tests were already making. Why Playwright Tests Pass Locally but Fail in CI CI machines behave differently CI runners are usually more constrained than developer machines. They often have less CPU, less memory, noisier d