t("foo", default: false) doesn't respect the default

[jdelStrother]

Steps to reproduce

Try to translate a key, supplying a default of false ( eg t("foo", default: false)).

Expected behavior

If the translation is missing, it returns false

Actual behavior

If the translation is missing, it returns <span class="translation_missing" title="translation missing: en.false">False</span>

This is also demonstrated in this sample project:
rails51.zip

System configuration

Rails version:

5.1.4

Ruby version:

2.3.4

This appears to be a change in the i18n gem since 0.8.3 - if you downgrade to 0.8.1, t("foo", default: false) return false.
However, the problem only occurs if you use Rails t helper - if you go via I18n.t("foo", default: false), it returns false regardless of the i18n version.

This was originally filed on the i18n repo at ruby-i18n/i18n#379.

[utilum]

@jdelStrother could you reproduce with an executable script based on https://github.com/rails/rails/blob/master/guides/bug_report_templates/generic_gem.rb ?

[jdelStrother]

Will see what I can do

[aditya-vector]

I think the issue is with Array being passed as an option here in the Rails helper.
The code in the helper encapsulates the default option to an array no matter what. And, thus on the I18n side when I run,
I18n.translate('foo', default: [false]) it returns "translation missing: en.foo"

And then, the helper transforms it to the message "<span class=\"translation_missing\" title=\"translation missing: en.false\">False</span>" here in the rescue block. I wonder if its an update on Rails side or I18n side that has caused this to happen.

[jdelStrother]

FWIW, a simple test case. For me, flipping between i18n 0.8.1 & 0.8.3 will fix/break the test.

# frozen_string_literal: true

gem "bundler", "< 1.16"

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"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails", tag: 'fd1304d'
  
  # gem "i18n", "0.8.1"
  gem "i18n", "0.8.3"
end

require "action_controller/railtie"

class TestApp < Rails::Application
  config.root = __dir__
  secrets.secret_key_base = "secret_key_base"

  config.logger = Logger.new($stdout)
  Rails.logger  = config.logger

  routes.draw do
    get "/" => "test#index"
  end
end

class TestController < ActionController::Base
  include Rails.application.routes.url_helpers

  def index
    render inline: "<%= t(:foo, default: false) || 'no default' %>"
  end
end

require "minitest/autorun"
require "rack/test"

class BugTest < Minitest::Test
  include Rack::Test::Methods

  def test_default_false_translations_should_return_false
    assert I18n.t(:foo, default: false) == false
    
    get "/"
    assert_equal "no default", last_response.body
  end

  private
    def app
      Rails.application
    end
end

[rafaelfranca]

If that is the case this is a i18n issue since they changed the behavior in a patch version.

[fatkodima]

Opened PR on i18n side ruby-i18n/i18n#399.

[y-yagi]

Fixed with ruby-i18n/i18n#399