DEV: Move logic for language support into translators

Author: nattsw

app/services/discourse_translator/base.rb

@@ -60,5 +60,12 @@ def self.get_text(topic_or_post)
         topic_or_post.title
       end
     end
+
+    def self.language_supported?(detected_lang)
+      raise NotImplementedError unless self.const_defined?(:SUPPORTED_LANG_MAPPING)
+      supported_lang = const_get(:SUPPORTED_LANG_MAPPING)
+      return false if supported_lang[I18n.locale].nil?
+      detected_lang != supported_lang[I18n.locale]
+    end
   end
 end

plugin.rb

@@ -50,10 +50,9 @@ module ::DiscourseTranslator
       Discourse.redis.sadd?(DiscourseTranslator::LANG_DETECT_NEEDED, object.id)
       false
     else
-      detected_lang !=
-        "DiscourseTranslator::#{SiteSetting.translator}::SUPPORTED_LANG_MAPPING".constantize[
-          I18n.locale
-        ]
+      "DiscourseTranslator::#{SiteSetting.translator}".constantize.language_supported?(
+        detected_lang,
+      )
     end
   end
 end

spec/services/base_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe DiscourseTranslator::Base do
+  class TestTranslator < DiscourseTranslator::Base
+    SUPPORTED_LANG_MAPPING = { en: "en", ar: "ar", es_MX: "es-MX", pt: "pt" }
+  end
+
+  class EmptyTranslator < DiscourseTranslator::Base
+  end
+
+  describe ".language_supported?" do
+    it "raises an error when the method is not implemented" do
+      expect { EmptyTranslator.language_supported?("en") }.to raise_error(NotImplementedError)
+    end
+
+    it "returns false when the locale is not supported" do
+      I18n.stubs(:locale).returns(:xx)
+      expect(TestTranslator.language_supported?("en")).to eq(false)
+    end
+
+    it "returns true when the detected language is not the current locale" do
+      I18n.locale = :pt
+      expect(TestTranslator.language_supported?("en")).to eq(true)
+      expect(TestTranslator.language_supported?("ar")).to eq(true)
+      expect(TestTranslator.language_supported?("es-MX")).to eq(true)
+    end
+
+    it "returns false when the detected language is the detected locale" do
+      I18n.locale = :pt
+      expect(TestTranslator.language_supported?("pt")).to eq(false)
+    end
+  end
+end