Country codes are 2 uppercase letters about i18n_extension HOT 1 CLOSED

You are right of course, but unfortunately the Locale class doesn't force you to use the correct standards for country and language. You can basically type whatever you want. As a result it's very easy to make mistakes, and the most common one is not using uppercase letters. Try it:

test("Is Locale standardized? No it's not. That's why I normalize it as lowercase.", () {
    expect(Locale("pt", "br").toString(), "pt_br");
    expect(Locale("pt", "BR").toString(), "pt_BR");
    expect(Locale("pt", "BR"), Locale("pt", "BR"));
    expect(Locale("pt", "br"), isNot(Locale("pt", "BR")));
  });

To make it case insensitive, I'm normalizing it in lowercase.

I suggest you open an issue to fix the Locale class itself. Once they fix it I can follow the standard. Or, if they don't, maybe in the future the i18n_extension could make sure the given country and language are following the standard, and then point out the Locale is invalid. But this would force me to validate the Locale, which I don't have enough knowledge to do.

from i18n_extension.