Set language to English

[hadley]

@MichaelChirico does this seem ok to you? (Since you're the only person I know who's testing translations). R CMD check already sets the language to English so we don't think this should affect much existing code.

Fixes #1213

[gaborcsardi]

Should we include a sentence about this in the list of things local_test_context() sets, up about line 44?

Btw. that line also needs a fix for RSTUDIO, which is now unset.

[MichaelChirico]

IINM it will work on Unix, but probably (?) not on Windows (though I do see a ✅ for the Windows GHA). We had some headaches getting non-English tests to work on Windows... see Rdatatable/data.table#4524.

I'm not sure if it's any easier a problem to specifically force English than it was for us to temporarily set Chinese.

For reference I think you're referring to this from WRE 1.3.1:

All these tests are run with collation set to the C locale, and for the examples and tests with environment variable LANGUAGE=en: this is to minimize differences between platforms.

There's also this in R administration 2.8 about testing R installation:

Sys.setenv(LC_COLLATE = "C", LC_TIME = "C", LANGUAGE = "en")

And I think our troubles were related to this note in R administration 7.2:

It is usually possible to change the language once R is running via (not Windows) Sys.setlocale("LC_MESSAGES", "new_locale"), or by setting an environment variable such as LANGUAGE, provided34 the language you are changing to can be output in the current character set. But this is OS-specific, and has been known to stop working on an OS upgrade.

[hadley]

I also have a vague recollection that the translation is cached, so that after an error message has been processed once, changing LANG doesn't have any effect.

[hadley]

Running the testthat revdeps now, just to double check that this won't accidentally break anything.

[hadley]

I individually checked the four failures — they seem unrelated to the language setting.