Test with a specific language/locale

Historically we have had headaches with international formats for numbers and dates based on the user’s browser language/locale.

It would be great to be able to set a specific language/locale for a test so I could confirm that numbers and dates work as expected for a Spanish user vs a US user etc.

We all seem to use commas, full stops differently in numbers for example so being able to test this would be a huge help!