A "no-op" policy to support feature-agnostic testing

[mustaqahmed]

While trying to write a (tentative) web-platform-test for Capability delegation, it seemed to me that adding a "no-op" feature to this list could be handy for testing. More precisely, this "no-op" feature would have an "always supported" state in the user agent, so a WPT could test a code path related to a passing policy without relying on a specific feature's state in the browser or Window.

One particular case I am trying to resolve: I want to test all errors in Step 8 of this proposed modification to HTML post-message algorithm. Now assume that "browser1" supports delegating only one feature, say "feature1", and "browser2" supports delegating only "feature2". In that case, I don't see a way to test all sub-steps of Step 8 in both these browsers. Note that the proposed Step 8 is feature-agnostic.

Any chance there is an known solution in the Permissions world already? @clelland

[flackr]

If needed, couldn't a WPT test loop through features until it found one that was supported? I feel like it's not a good idea to add a "no-op" feature just for testing and try to ensure it behaves the same in browsers as delegating regular features.

[mustaqahmed]

@clelland: assuming this is a standard "list" we can loop through in tests, do we have an exposed data structure to find them? Otherwise we will have to hardcode them in tests for now.