overriding intl.accept_languages and intl.locale.requested does not take effect

[cfm]

In freedomofpress/securedrop#7354, we're trying to test our localization by overriding the Accept-Language header via Firefox's intl.accept_languages. In https://gist.github.com/cfm/8a4dddcee3e993998ec4d68e123da89d I've created a minimal reproduction that shows that neither of the following approaches works in tbselenium:

# Manually setting this value in "about:config" is sufficient in an interactive Firefox session.
options.set_preference("intl.accept_languages", LANG)

# Manually setting this value in "about:config" is sufficient in an interactive Tor Browser session.
options.set_preference("intl.locale.requested", LANG)

Tor Browser tickets like tor-browser#41930 and tor-browser#41339 point to the complexity of these preferences but suggest that they should take overrides as usual, which is why I suspect this is an interaction with tbselenium.

[gunesacar]

Could you try setting this pref using this utility function?
https://github.com/webfp/tor-browser-selenium/blob/main/tbselenium/utils.py#L96

(see, an example use here)

I've had cases where pref changes were not recognized, and the above method (which uses chrome privileges) was the solution. LMK if that doesn't work and I'll dig deeper.

PS: Sorry for the delay in responding. I was out of office.

[gunesacar]

Sample code to overwrite the Accept-Language header: https://gist.github.com/gunesacar/6f160016546c97d010544311076f06c7

Prints: Accept-Language=de,en-US;q=0.7,en;q=0.3

Another example, iterating over different locales. It also prints navigator.language(s), which are not overwritten!:
https://gist.github.com/gunesacar/71a3a80c1460e7ae6a1d0d151f3f4264

[cfm]

Thank you, @gunesacar! I was just looking at this and reached basically the same diff. Thanks for pointing me towards set_tbb_pref().

[gunesacar]

Great! Feel to reach out for similar issues.