PSI Report erroneously displays "Emulated Desktop"

[patrickhulce]

FAQ

• Yes, my issue is not about variability or throttling.
• Yes, my issue is not about a specific accessibility audit (file with axe-core instead).

URL

https://blog.patrickhulce.com

What happened?

When looking at the PageSpeed report for Mobile, the info box displays "Emulated Desktop" and lists screen emulation values as undefined.

What did you expect?

I expected to see "Emulated Mobile" and the screen resolution / DPR that was used.

What have you tried?

Shouting out to my favorite Lighthouse team :)

How were you running Lighthouse?

PageSpeed Insights

Lighthouse Version

9.6.6

[connorjclark]

https://googlechrome.github.io/lighthouse/viewer/?gist=9e3e31748ddad6fe33ed84990e1fe94f lhr from PSI

settings.screenEmulation is an empty object in the renderer for this LHR, which fails us here.

[connorjclark]

Caused by rolling 10.0 renderer, and now we read from screenEmulation in the config, which is not represented in the lighthouse proto. Rolling back now.

lighthouse/report/renderer/report-utils.js

Lines 202 to 204 in 94e4399

	const isScreenEmulationMobile = settings.channel === 'devtools' ?
	settings.formFactor === 'mobile' :
	settings.screenEmulation.mobile;

We could do the same thing we did previously for devtools (formFactor is present). Or we could add screenEmulation to the proto.

[connorjclark]

Rolled back last Friday, and #14809 will prevent this in the future.

Thanks @patrickhulce!