User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:25.0) Gecko/20100101 Firefox/25.0 (Beta/Release) Build ID: 20131025151332 Steps to reproduce: I would like to be able to set a list of URL or URL fragments that should not be requested when the developer tools network panel is open, making it easy to test impact of third-party services failure.

In terms of UI, I think we could re-use the "eye" icon used for blackboxing and disabling CSS files.

Could be useful to simulate these: * a request taking longer. * a request never answering (kind of the same) * a request returning an error instead of a real thing

FWIW, the Chrome DevTools just got that feature: https://developers.google.com/web/updates/2017/04/devtools-release-notes#block-requests (In reply to Julien Wajsberg [:julienw] from comment #2) > Could be useful to simulate these: > * a request taking longer. > * a request never answering (kind of the same) > * a request returning an error instead of a real thing I like those ideas a lot, though I'd say they are too much for the first iteration. So, in this bug, let's focus on blocking the requests completely (This is also what the Chrome DevTools seem to do.) and file new ones to allow throttling and failing individual requests. Sebastian

Was just mentioned on https://hacks.mozilla.org/2017/09/developer-edition-devtools-update-now-with-photon-ui/comment-page-1/#comment-21810