Add missing-plural-keys

[Gargron]

Fix #308

[Gargron]

@glebm So here's the deal. If you require i18n/tasks from a Rails app that has rails-i18n as a dependency, then the method works and returns all nodes that have missing pluralizations.

But from within the standalone executable, it does not work. I cannot figure out how to include pluralization data from rails-i18n into the gem itself. Without pluralization data, nothing can be done.

[glebm]

I cannot figure out how to include pluralization data from rails-i18n into the gem itself

You'd need to add dependency on rails-i18n to this gem.

I also think this should be part of the missing task. Tasks like add/translate-missing should also have special behaviour for plural keys. What do you think?

You'd need to add a new missing "type" :plural here and go from there:

i18n-tasks/lib/i18n/tasks/missing_keys.rb

Lines 19 to 21 in 9a4f7a1

	# @param types [:used, :diff] all if `nil`.
	# @return [Siblings]
	def missing_keys(locales: nil, types: nil, base_locale: nil)

[Gargron]

Okay, I was able to add rails-i18n as a dependency. I thought it would be more trouble because all that does by itself is define a Railtie, which wouldn't work without a Rails environment, but I was able to use on of the methods to just load all pluralization rules. rails-i18n itself defines i18n-tasks as a development dependency, I hope there's no ill effects from that circularity...

Now, I ensured that missing-plural-keys works as a command. I'll try to move it to the missing keys in a different commit...

[Gargron]

There are some rubocop offences I can't really fix

[glebm]

Feel free to selectively disable Rubocop checks where it makes sense (see https://github.com/rubocop-hq/rubocop/blob/master/manual/configuration.md#disabling-cops-within-source-code)

rails-i18n itself defines i18n-tasks as a development dependency, I hope there's no ill effects from that circularity

Curious. I guess we'll soon find out. 😄

[Gargron]

Done!

It's now part of missing. I have also removed some dead code that was not called from anywhere, such as glyph/summary definitions for the missing types, and the glyph renderer in the terminal report.

Also, rails-i18n does not call i18n-tasks code, only the stand-alone executable, so I don't think it will be a problem.

I do not have the bandwidth to implement an add-missing behaviour here. My guess is just that if the translations for all plural keys are identical, the translation should be turned from a tree to a single leaf. It would be convenient but I don't really need it right now.

[glebm]

Thank you! This and interpolations are great additions!

[SirRawlins]

@Gargron - Is there any way to ignore missing plural keys? I've tried adding the missing keys to ignore_missing missing array in my configuration, however, they still get flagged as missing.