[WebDriver BiDi] emulate network offline

[sadym-chromium]

Respect WebDriver BiDi emulated network offline condition in navigator.onLine property.

• At least two implementers are interested (and none opposed):
  • Chromium
  • Mozilla
• Tests are written and can be reviewed and commented upon at:
  • [wdspec] emulation.setNetworkConditions:offline web-platform-tests/wpt#55300
• Implementation bugs are filed:
  • Chromium: feat: implement emulation.setNetworkConditions:offline GoogleChromeLabs/chromium-bidi#3819
  • Gecko: https://bugzilla.mozilla.org/show_bug.cgi?id=1993079
  • WebKit: N/A
  • Deno (only for timers, structured clone, base64 utils, channel messaging, module resolution, web workers, and web storage): N/A
  • Node.js (only for timers, structured clone, base64 utils, channel messaging, and module resolution): N/A
• Corresponding HTML AAM & ARIA in HTML issues & PRs: N/A
• MDN issue is filed: N/A
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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/infrastructure.html ( diff )
/system-state.html ( diff )

[annevk]

I would suggest we introduce an "is online" abstraction in Fetch as part of whatwg/fetch#1852 and then make this getter return "is online".

[sadym-chromium]

I would suggest we introduce an "is online" abstraction in Fetch as part of whatwg/fetch#1852 and then make this getter return "is online".

Ack, I will do

[noamr]

Informal LGTM

[sadym-chromium]

I would suggest we introduce an "is online" abstraction in Fetch as part of whatwg/fetch#1852 and then make this getter return "is online".

The only concern is that in the fetch spec we would still need to invoke WebDriver BiDi twice: in fetch and in "is online" getter.

[annevk]

Oh why? I thought that fetch could also use "is online". I guess in theory that would introduce novel behavior due to the extra condition, but in practice it already behaves like that when you're offline, no?

[sadym-chromium]

Oh why? I thought that fetch could also use "is online". I guess in theory that would introduce novel behavior due to the extra condition, but in practice it already behaves like that when you're offline, no?

I think with the current wording (in html) it's a chicken-egg problem:

The onLine attribute must return false if the user agent will not contact the network when the user follows links or when a script requests a remote page (or knows that such an attempt would fail), and must return true otherwise.

I'm not an expert here, but if you insist I can move this definition to the fetch spec. Please let me know if this is the preferred.

[annevk]

I'm not either. I was thinking we'd change that hand-wavy definition to another. Something like:

A user agent is considered to be online when the user agent assumes it has internet access.

[sadym-chromium]

I'm not either. I was thinking we'd change that hand-wavy definition to another. Something like:

A user agent is considered to be online when the user agent assumes it has internet access.

So you want the HTML spec to refer the Fetch's environment is online, which in turn will refer to user agent is physically offline and environment is emulated offline (we need environment to get WebDriver BiDi Offline emulation status)?

[annevk]

Yeah, and Fetch's fetch algorithm would depend on the same primitive. Essentially the same thing we did as with the default User-Agent value, to avoid duplicating ourselves and making sure it all works in a consistent fashion.

[sadym-chromium]

Yeah, and Fetch's fetch algorithm would depend on the same primitive. Essentially the same thing we did as with the default User-Agent value, to avoid duplicating ourselves and making sure it all works in a consistent fashion.

Done in whatwg/fetch#1852