new_audit: add responsiveness metric for timespans

[brendankenny]

Part of #13916

Adds an experimental version of https://web.dev/responsiveness/ for timespans.

Also adds a new timespan test trace from a page with interaction events coming from both the main frame and a child iframe.

[brendankenny]

a lot of these TODOs are items in #13916

[brendankenny]

@paulirish do you have feelings about what we should call the audit if we want the name to stand the test of time?

[paulirish]

on the crux side we're using an experimental_ prefix in both BQ and API. So while we've never done that here, that'd be consistent and fairly reasonable.

[brendankenny]

experimental-interaction-to-next-paint it is :)

[brendankenny]

this is the same weight as TBT so it's 50/50, but maybe we don't care because timespan reports don't show the weighted score?

[adamraine]

If this is going to be a diagnostic in navigation mode, it might be helpful to make the score 0, but someone reading the config wouldn't know that it's still important for timespans.

[brendankenny]

If this is going to be a diagnostic in navigation mode, it might be helpful to make the score 0, but someone reading the config wouldn't know that it's still important for timespans.

yeah, makes sense, done. The scoring is confusing at the JSON level in timespans, but scoring is confusing in timespans, so that's nothing new :)

[adamraine]

Could add a supportedModes: ['timespan'] to the meta for now.

Also throttlingMethod should always be overriden in timespan mode:

lighthouse/lighthouse-core/fraggle-rock/config/config.js

Lines 170 to 176 in 6ba8dc8

	function overrideSettingsForGatherMode(settings, context) {
	if (context.gatherMode === 'timespan') {
	if (settings.throttlingMethod === 'simulate') {
	settings.throttlingMethod = 'devtools';
	}
	}
	}

[brendankenny]

Added supportedModes: ['timespan'], but kept the explicit simulate check. I'd like to keep the throttlingMethod support independent of the gatherMode until we figure out how good the responsiveness simulation can be

[brendankenny]

hmm:

Summary of all failing tests
FAIL lighthouse-core/test/fraggle-rock/scenarios/api-test-pptr.js (44.918 s)
  ● Fraggle Rock API › startTimespan › should compute results from timespan after page load

    expect(received).toMatchInlineSnapshot(snapshot)

    Snapshot name: `Fraggle Rock API startTimespan should compute results from timespan after page load 2`

    Snapshot: 18
    Received: 19

      142 |       expect(auditResults.length).toMatchInlineSnapshot(`45`);
      143 |
    > 144 |       expect(notApplicableAudits.length).toMatchInlineSnapshot(`18`);
          |                                          ^
      145 |       expect(notApplicableAudits.map(audit => audit.id)).not.toContain('total-blocking-time');
      146 |
      147 |       expect(erroredAudits).toHaveLength(0);

      at Object.<anonymous> (lighthouse-core/test/fraggle-rock/scenarios/api-test-pptr.js:144:42)

ok, so update:

-      expect(notApplicableAudits.length).toMatchInlineSnapshot(`18`);
+      expect(notApplicableAudits.length).toMatchInlineSnapshot(`19`);

and now

FAIL lighthouse-core/test/fraggle-rock/scenarios/api-test-pptr.js (45.002 s)
  ● Fraggle Rock API › startTimespan › should compute results from timespan after page load

    expect(received).toMatchInlineSnapshot(snapshot)

    Snapshot name: `Fraggle Rock API startTimespan should compute results from timespan after page load 2`

    Snapshot: 19
    Received: 18

      142 |       expect(auditResults.length).toMatchInlineSnapshot(`45`);
      143 |
    > 144 |       expect(notApplicableAudits.length).toMatchInlineSnapshot(`19`);
          |                                          ^
      145 |       expect(notApplicableAudits.map(audit => audit.id)).not.toContain('total-blocking-time');
      146 |
      147 |       expect(erroredAudits).toHaveLength(0);

      at Object.<anonymous> (lighthouse-core/test/fraggle-rock/scenarios/api-test-pptr.js:144:42)

@adamraine any thoughts?

[adamraine]

Could you add an m10X to this filename.

[brendankenny]

Could you add an m10X to this filename.

done

[adamraine]

@adamraine any thoughts?

I'll investigate

[adamraine]

Overall LGTM, excited to see this in action