From af76109eb1bbfb862c72aab54f5dedd785b0f170 Mon Sep 17 00:00:00 2001
From: Alex Ghiculescu <alex@tanda.co>
Date: Wed, 16 Oct 2019 11:39:17 -0500
Subject: [PATCH] Add tests for existing behavior

---
 test/backend/pluralization_fallback_test.rb | 69 +++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 test/backend/pluralization_fallback_test.rb

diff --git a/test/backend/pluralization_fallback_test.rb b/test/backend/pluralization_fallback_test.rb
new file mode 100644
index 00000000..351aa6a3
--- /dev/null
+++ b/test/backend/pluralization_fallback_test.rb
@@ -0,0 +1,69 @@
+require 'test_helper'
+
+class I18nBackendPluralizationFallbackTest < I18n::TestCase
+  class Backend < I18n::Backend::Simple
+    include I18n::Backend::Pluralization
+    include I18n::Backend::Fallbacks
+  end
+
+  def setup
+    super
+    I18n.default_locale = :'en'
+    I18n.backend = Backend.new
+
+    store_translations('en', cat: { zero: 'cat', one: 'cat', other: 'cats' })
+    store_translations('en-US', cat: { zero: 'no cat', one: nil, other: 'lots of cats' })
+
+    store_translations('ru', cat: { one: 'кот', few: 'кошек', many: 'кошка', other: 'кошек' })
+    # probably not a real locale but just to demonstrate
+    store_translations('ru-US', cat: { one: nil, few: nil, many: nil, other: nil })
+    store_translations('ru', i18n: { plural: { rule: russian_rule }})
+  end
+
+  test "fallbacks: nils are ignored and fallback is applied" do
+    assert_equal "no cat", I18n.t("cat", count: 0, locale: "en-US")
+    assert_equal "cat", I18n.t("cat", count: 0, locale: "en")
+
+    assert_equal "cat", I18n.t("cat", count: 1, locale: "en-US")
+    assert_equal "cat", I18n.t("cat", count: 1, locale: "en")
+
+    assert_equal "lots of cats", I18n.t("cat", count: 2, locale: "en-US")
+    assert_equal "cats", I18n.t("cat", count: 2, locale: "en")
+  end
+
+  test "fallbacks: nils are ignored and fallback is applied, with custom rule" do
+    # more specs: https://github.com/svenfuchs/rails-i18n/blob/master/spec/unit/pluralization/east_slavic.rb
+    assert_equal "кошка", I18n.t("cat", count: 0, locale: "ru")
+    assert_equal "кошка", I18n.t("cat", count: 0, locale: "ru-US")
+
+    assert_equal "кот", I18n.t("cat", count: 1, locale: "ru")
+    assert_equal "кот", I18n.t("cat", count: 1, locale: "ru-US")
+
+    assert_equal "кошек", I18n.t("cat", count: 2, locale: "ru")
+    assert_equal "кошек", I18n.t("cat", count: 2, locale: "ru-US")
+
+    assert_equal "кошек", I18n.t("cat", count: 1.5, locale: "ru")
+    assert_equal "кошек", I18n.t("cat", count: 1.5, locale: "ru-US")
+  end
+
+  private
+
+  # copied from https://github.com/svenfuchs/rails-i18n/blob/master/lib/rails_i18n/common_pluralizations/east_slavic.rb
+  def russian_rule
+    lambda do |n|
+      n ||= 0
+      mod10 = n % 10
+      mod100 = n % 100
+
+      if mod10 == 1 && mod100 != 11
+        :one
+      elsif (2..4).include?(mod10) && !(12..14).include?(mod100)
+        :few
+      elsif mod10 == 0 || (5..9).include?(mod10) || (11..14).include?(mod100)
+        :many
+      else
+        :other
+      end
+    end
+  end
+end