allow disabling fallback explicitly when calling translate

[ignatiusreza]

e.g. by doing I18n.translate(:key, :fallback => false)

note that currently, we sort of able to do this by doing I18n.translate(:key, :fallback => true), which are quite a confusing behavior, introduced -- I assumed -- unintentionally because we're modifying options.. so this PR does have backward incompatibility changes, even though it's one that was not officially supported before?

another note is, in the wiki for fallbacks, we have something like:

You can skip the fallback and return the default by passing in an empty fallback array

I18n.translate(:foo, :locale => :de, :default => 'Default Foo', :fallbacks => []) # => 'Default Foo'

which does not seems to works.. if what the wiki is saying is the preferred way for supporting disabling fallback, I'm happy to change this PR to do just that, though, I must say that having both fallback and fallbacks as part of the options will be confusing..

[ignatiusreza]

seems like test is broken in master too, opened a separate PR to fix it at #355 .. will rebase later..

[radar]

Does I18n.translate(:foo, :locale => :de, :default => 'Default Foo', :fallbacks => []) work already with the master version? Note that the option here is fallbacks (plural) and not fallback.

[ignatiusreza]

nope, as far as I can tell, fallbacks option doesn't work in master, despite what the wiki are saying..

[radar]

@ignatiusreza Would you please be able to provide me with a small reproduction repo that I could use to investigate this issue? I think you'd be better at coming up with one than me because it sounds like you understand what's happening here.

Please provide steps to reproduce the issue and expected/actual outcomes as well.

From that point I should have enough information to investigate.

Thanks!

[ignatiusreza]

Sure @radar ! Would something like the following be okay?

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"

  # use this to see test #2 pass, while #1 & #3 fails
  gem "i18n"

  # use this to see test #3 pass, while #1 & #2 fails
  # gem "i18n", github: 'ignatiusreza/i18n', branch: 'disable_fallback'

  gem "minitest"
  gem "test_declarative"
end

require "i18n"
require "minitest/autorun"

# Ensure backward compatibility with Minitest 4
Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)

class I18nBackendFallbacksTranslateTest < Minitest::Test
  # ehem.. I don't actually suck, but it's easier to follow if the test are sorted.. :p
  i_suck_and_my_tests_are_order_dependent!

  class Backend < I18n::Backend::Simple
    include I18n::Backend::Fallbacks
  end

  def setup
    super

    I18n.enforce_available_locales = false

    I18n.backend = Backend.new
    I18n.backend.store_translations(:en, :foo => 'Foo in :en', :bar => 'Bar in :en')
    I18n.backend.store_translations(:de, :bar => 'Bar in :de')
  end

  def teardown
    I18n.locale = nil
    I18n.default_locale = nil
    I18n.load_path = nil
    I18n.available_locales = nil
    I18n.backend = nil
    I18n.default_separator = nil
    I18n.enforce_available_locales = true

    super
  end

  test "1. disable fallback using :fallbacks => []" do
    # syntax taken from wiki, but it doesn't works
    # ref: https://github.com/svenfuchs/i18n/wiki/Fallbacks#providing-a-default
    assert_equal 'Default Foo', I18n.t(:foo, :locale => :de, :default => 'Default Foo', :fallbacks => [])
  end

  test "2. disable fallback using :fallback => true" do
    # side effect of modifying options[:fallback]
    # ref: https://github.com/svenfuchs/i18n/commit/957145ef85875b913a93502111368b4fc2c67fd5
    assert_equal 'Default Foo', I18n.t(:foo, :locale => :de, :default => 'Default Foo', :fallback => true)
  end

  test "3. disable fallback using :fallback => false" do
    # suggested approach
    # ref: https://github.com/svenfuchs/i18n/pull/354
    assert_equal 'Default Foo', I18n.t(:foo, :locale => :de, :default => 'Default Foo', :fallback => false)
  end
end

[radar]

Thank you @ignatiusreza. This is excellent.

I don't see anywhere in the code that uses the passed-in fallbacks option, so I am guessing the wiki is out-of-date with that one.

I have taken a look at this issue this morning and I can't figure out how to fix it without breaking other things. Maybe someone smarter than me can figure it out?

[ignatiusreza]

I'm sorry, but could you help clarify in what you meant by without breaking other things.? since test passes even with my changes.. or are there any other scenario which are untested that could be broken?

if you're worried about making fallback: true stop working, then maybe we can have a deprecation cycle which provide a deprecation warning when translate is called with explicit truthy value for options[:fallback]? though, since we're retiring an undocumented behavior, I'm not sure if it's worth it to have a deprecation cycle..

[radar]

Sorry, I had forgotten this was a PR and I was writing those replies on my phone. Now that I'm on a computer, I can see better :) Sorry for that confusion.

---

The code looks great and the tests are all happy, and so am I :)

[ignatiusreza]

not a problem.. thanks for the merge 👍

[jbourassa]

We were using fallback: [] as a way of having no fallbacks (no s at fallback). That worked, although incorrectly documented in the Wiki. I was wondering why it stopped working so I git bisect'ed my way to here. I think it's a good change, it is almost 1 year old and I don't see any complaints about it, so I'll just update the wiki and our codebase – I don't think it's worth resurrecting the old behaviour at this point.

[radar]

@jbourassa Thanks for the comment and for updating the wiki :)