virtual/not-site-per-process

Summary

Layout tests use the default site isolation from the platform they are run on. For example, strict site isolation (aka site-per-process) is used on desktop platforms.

Additionally, on platforms where strict site isolation is enabled, layout tests opt into slightly stricter isolation and enabling isolating same-site origins used by Web Platform Tests. This ensures that features covered by WPT also provide sufficient coverage of how these feature behave in presence of out-of-process iframes.

Tests under virtual/not-site-per-process are run with --disable-site-isolation-trials cmdline flag which turns off site isolation. This is needed to preserve test coverage provided by around 60 tests that fail when run with site isolation.

When modifying the list of files that behave differently with and without OOPIFs, please consider modifying all the locations below:

• LayoutTests/VirtualTestSuites (virtual/not-site-per-process suite)
• LayoutTests/virtual/not-site-per-process/README.md
• LayoutTests/TestExpectations and/or LayoutTests/NeverFixTests (“Site Isolation failures” section)

Tests incompatible with WPT origin isolation

The following tests modify document.domain and are therefore incompatible with isolation of WPT origins. The tests need to stay under virtual/not-site-per-process forever. These tests are covered by LayoutTests/NeverFixTests expectations file.

• external/wpt/html/browsers/origin/relaxing-the-same-origin-restriction
• external/wpt/FileAPI/url/multi-global-origin-serialization.sub.html
• external/wpt/dom/events/EventListener-incumbent-global-1.sub.html
• external/wpt/dom/events/EventListener-incumbent-global-2.sub.html
• external/wpt/html/browsers/history/the-location-interface/allow_prototype_cycle_through_location.sub.html
• external/wpt/html/browsers/history/the-location-interface/location-prototype-setting-same-origin-domain.sub.html
• external/wpt/html/browsers/origin/cross-origin-objects/cross-origin-objects-on-new-window.html
• external/wpt/html/browsers/the-windowproxy-exotic-object/windowproxy-prototype-setting-same-origin-domain.sub.html
• external/wpt/html/infrastructure/safe-passing-of-structured-data/shared-array-buffers/window-domain-success.sub.html
• external/wpt/html/infrastructure/safe-passing-of-structured-data/shared-array-buffers/window-similar-but-cross-origin-success.sub.html
• external/wpt/wasm/serialization/module/window-domain-success.sub.html
• external/wpt/wasm/serialization/module/window-similar-but-cross-origin-success.sub.html

Tests that need further investigation and/or decisions

Remaining tests need further investigation as they may either 1) hide previously unknown OOPIF-related bugs or 2) expose known OOPIF-related differences in product behavior or 3) expose known OOPIF-support issues in tests or in the test harness. Over time, such tests should be removed from virtual/not-site-per-process. These tests are covered by LayoutTests/TestExpectations file.