Specify network body data collection for cached responses

[juliandescottes]

With the current spec, the hook for cloning the body to collect responses in BiDi should be done at https://fetch.spec.whatwg.org/#ref-for-concept-body-stream%E2%91%A0%E2%91%A1:~:text=Set%20response%E2%80%99s%20body%20to%20a%20new%20body%20whose%20stream%20is%20stream%2E

However this excludes cached responses. At the moment it seems Chrome is returning the body for all cached responses, while Firefox doesn't.

I think we should probably try as much as possible to return bodies whenever possible but we should still discuss if we want to do that for responses which don't use the network at all.

Note that in Firefox we don't really have access to cached bodies for some resources (eg stylesheets) See https://bugzilla.mozilla.org/show_bug.cgi?id=1981164

[css-meeting-bot]

The Browser Testing and Tools Working Group just discussed Data collection for cached reponses.

The full IRC log of that discussion

<AutomatedTester> topic: Data collection for cached reponses
<AutomatedTester> github: https://github.com//issues/985
<AutomatedTester> jdescottes: data collection for cached responses. the current spec is has that we get a stream from fetch but we don't have anything coming from the cached version
<sadym> q+
<AutomatedTester> ... my feeling is that we should consistently return data even if it doesnt go over the network
<AutomatedTester> ... or should we have it handle the cached version consistently?
<AutomatedTester> ack next
<jdescottes> q+
<AutomatedTester> sadym: could we start with WPT tests ? to verify that we have the same behaviour
<AutomatedTester> ack next
<AutomatedTester> jdescottes: we can, we have mozilla specific wpt test that does that
<AutomatedTester> ... in chromium it does it for all where firefox doesnt do that for css or images
<AutomatedTester> ... we can have the spec to have it say to return a response text
<jgraham> q+
<AutomatedTester> ack next
<AutomatedTester> jgraham: if the spec doesn't say that we should have the right response... i'm not sure what gecko is doing here
<AutomatedTester> ... we need to make it consistent as authors don't expect to have inconsistency here
<AutomatedTester> q?