No way to test translated strings

[mks-h]

There is currently no way to force gettext functions to return specific strings. This means I cannot test if the macros I'm working on at #89 fall back to default strings when returned ones are broken. I believe there are two ways to solve the problem:

1. For testing, use container populated with translation files;
2. Fake gettext functions and use some magic of constants to specify which string to return.

I find the first option too cumbersome, so I'll investigate second.

[Minoru]

I'm on the road right now, so just a couple pointers. I can clarify on Sunday if you have questions.

bindtextdomain() takes a path to a directory with a structure similar to /usr/locale. We can create such a directory and populate it with known data, which we will then request via gettext() and friends.

The data is described by a PO file, and compiled into MO files which are put into the locator directory under an appropriate language tag. See gettext manual and /usr/locale on your own machine.

[mks-h]

We can create such a directory and populate it with known data, which we will then request via gettext() and friends.

Yeah, but we will have to initialize it before testing somehow, which is cumbersome.

I have came up with a solutrion that will suffice for now. The idea is to, in each testing function, have an inlined module with a "gettextrs" name that declares a fake gettext function and reexports formatter from the actual gettextrs. Like so:

#[test]
fn nothing_to_format_translated() {
    mod gettextrs {
        pub use ::gettextrs::formatter;
        pub fn gettext<T: Into<String>>(_msgid: T) -> String {
                "Привіт, світ!".into()
        }
    }

    assert_eq!(gettext!("Hello, World!"), "Привіт, світ!");
}

I've put up a declarative macro that simplifies the generation of a module. So, in the end, it looks like so:

#[test]
fn nothing_to_format_translated() {
    fake!(gettext, "Привіт, світ!");

    assert_eq!(gettext!("Hello, World!"), "Привіт, світ!");
}

This approach limits me to using one message per test, which is fair. The problem is that it works because procedural gettext macros use gettextrs::gettext(...) path's which can be confused with a gettextrs module. I could have used ::gettextrs::gettext(...), which can't be confused, but then there is also a feature in cargo that allow renaming dependencies for which I have to get the actual name of the crate anyway... So I'll deal with that later.

I'll leave this issue open for now since it will have to be revisited.

[mks-h]

The other problem is that I have to duplicate function definitions, which might get out of sync with actual implementations. Not an issue today, but it can certainly become one.