Test: Added locale files test

lib/locales/cs.yml

@@ -1,4 +1,4 @@
-# :czech pluralization (see https://github.com/ddnexus/pagy/blob/master/lib/pagy/i18n.rb)
+# :west_slavic pluralization (see https://github.com/ddnexus/pagy/blob/master/lib/pagy/i18n.rb)
 
 cs:
   pagy:

lib/locales/sw.yml

@@ -1,4 +1,4 @@
-# :one_other pluralization
+# :one_other pluralization (see https://github.com/ddnexus/pagy/blob/master/lib/pagy/i18n.rb)
 
 sw:
   pagy:

lib/locales/vi.yml

@@ -1,4 +1,4 @@
-# :other pluralization (see https://github.com/ddnexus/pagy/blob/master/lib/locales/utils/p11n.rb)
+# :other pluralization (see https://github.com/ddnexus/pagy/blob/master/lib/pagy/i18n.rb)
 
 vi:
   pagy:

test/pagy/i18n_locales_test.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require_relative '../test_helper'
+
+describe 'pagy/locales' do
+  let(:rules) { Pagy::I18n::P11n::RULE.keys }
+  let(:counts) do
+    {
+      arabic:             %w[zero one two few many other],
+      east_slavic:        %w[one few many other],
+      one_other:          %w[one other],
+      one_two_other:      %w[one two other],
+      one_upto_two_other: %w[one other],
+      other:              %w[other],
+      polish:             %w[one few many other],
+      west_slavic:        %w[one few other]
+    }
+  end
+
+  # locale files loop
+  Pagy.root.join('locales').each_child do |f|
+    next unless f.extname == '.yml'
+
+    message = "locale file #{f}"
+    locale  = f.basename.to_s[0..-5]
+    comment = f.readlines.first.to_s.strip
+    rule    = comment.to_s.split[1][1..-1].to_s.to_sym
+
+    it 'includes a comment with the pluralization rule and the i18n.rb reference' do
+      _(rules).must_include rule, message
+      _(comment).must_match 'https://github.com/ddnexus/pagy/blob/master/lib/pagy/i18n.rb', message
+    end
+    it 'defines and matches the locale pluralization rule' do
+      _(Pagy::I18n::P11n::LOCALE[locale]).must_equal Pagy::I18n::P11n::RULE[rule], message
+    end
+    it 'pluralizes item_name according to the rule' do
+      hash      = YAML.safe_load(f.read)
+      item_name = hash[locale]['pagy']['item_name']
+      case item_name
+      when String
+        _(rule).must_equal :other
+      when Hash
+        _(item_name.keys - counts[rule]).must_be_empty
+      else
+        raise StandardError, "item_name must be Hash or String"
+      end
+    end
+  end
+end