`Emulation.setEmulatedMedia` not working?

[gerjomarty]

Hello!

I'm trying to use the Emulation.setEmulatedMedia query to set the media query to print, but I get the error:

'Emulation.setEmulatedMedia' wasn't found (Ferrum::BrowserError)

Here is a single file reproduction of the problem:

require "bundler/inline"

gemfile do
  source "https://rubygems.org"
  gem "ferrum"
end

browser = Ferrum::Browser.new

browser.command("Emulation.setEmulatedMedia", media: "print")
browser.go_to("https://lachy.id.au/dev/css/tests/media/print/html401-print.html")

% ruby test.rb
/Users/me/.asdf/installs/ruby/3.1.4/lib/ruby/gems/3.1.0/gems/ferrum-0.13/lib/ferrum/browser/client.rb:97:in `raise_browser_error': 'Emulation.setEmulatedMedia' wasn't found (Ferrum::BrowserError)
	from /Users/me/.asdf/installs/ruby/3.1.4/lib/ruby/gems/3.1.0/gems/ferrum-0.13/lib/ferrum/browser/client.rb:49:in `command'
	from /Users/me/.asdf/installs/ruby/3.1.4/lib/ruby/gems/3.1.0/gems/ferrum-0.13/lib/ferrum/browser.rb:209:in `command'
	from test.rb:10:in `<main>'

I'm not entirely sure where the issue lies here, apologies if the root cause is actually somewhere down the line.

[ducharmemp]

This is an old issue but setEmulatedMedia appears to be a page-level command, not a browser command. To command the page you have to call browser.page.command instead.

As an example for prefers-reduced-motion:

browser.page.command('Emulation.setEmulatedMedia', features: [{name: 'prefers-reduced-motion', value: 'reduce'}])