chromium/third_party/blink/web_tests/http/tests/serviceworker/README.md

This directory contains Chromium-specific tests for service workers, i.e., tests
that are not suitable for adding to [Web Platform
Tests](/docs/testing/web_platform_tests.md). Most new tests should be added to
external/wpt/service-workers instead of here.

Tests in this directory should have a comment explaining why the test cannot be
upstreamed to WPT. Tests here fall into one or more of the following categories:

1) Tests that assert behavior that contradicts the specification. Ideally we
would fix Chromium's behavior, but in the meantime sometimes need to maintain
the deprecated behavior until it can be fixed.

Instead of a Chromium-only test, it's preferable to have a WPT test that asserts
the correct things, and an -expected.txt file for Chromium's failing
expectations. However, in some cases that would not provide sufficient test
coverage for Chromium's spec-violating behavior.

When tests like this are added, they should have a comment at the top pointing
to the correct WPT test, and link to the bug tracking removal of the Chromium
test.

2) Tests that exercise behavior like (not) crashing and garbage collection that
are only useful because of Chromium-specific details. Consider making any test
that looks like it would be useful for other browsers a WPT test.

3) Tests that require use of the Internals API or other Chromium-specific APIs.