FIX: Also strip anchor tags when detecting language (#187)

When @ mentioning a user, there is a chance that the username is detected as the language rather than the post content itself. Stripping the anchor tag will help with better language detection.

Author: nattsw

app/services/discourse_translator/base.rb

@@ -72,14 +72,17 @@ def self.language_supported?(detected_lang)
 
     private
 
-    def self.strip_img_for_detection(detection_text)
+    def self.strip_tags_for_detection(detection_text)
       html_doc = Nokogiri::HTML::DocumentFragment.parse(detection_text)
       html_doc.css("img").remove
+      html_doc.css("a.mention,a.lightbox").remove
       html_doc.to_html
     end
 
     def self.text_for_detection(topic_or_post)
-      strip_img_for_detection(get_text(topic_or_post).truncate(DETECTION_CHAR_LIMIT, omission: nil))
+      strip_tags_for_detection(
+        get_text(topic_or_post).truncate(DETECTION_CHAR_LIMIT, omission: nil),
+      )
     end
 
     def self.text_for_translation(topic_or_post)

spec/services/base_spec.rb

@@ -41,6 +41,27 @@ class EmptyTranslator < DiscourseTranslator::Base
       expect(DiscourseTranslator::Base.text_for_detection(post)).to eq("")
     end
 
+    it "strips @ mention anchor tags" do
+      post.cooked = "<a class='mention' href='/u/cat' >cat</a>"
+      expect(DiscourseTranslator::Base.text_for_detection(post)).to eq("")
+    end
+
+    it "strips lightbox anchor tags" do
+      post.cooked = "<a class='lightbox' href='http://cloudfront.net/image.png' />"
+      expect(DiscourseTranslator::Base.text_for_detection(post)).to eq("")
+    end
+
+    it "leaves other anchor tags alone" do
+      cooked = <<~HTML
+        <p>
+          <a href="http://cat.com/image.png"></a>
+          <a class="derp" href="http://cat.com/image.png"></a>
+        </p>
+        HTML
+      post.cooked = cooked
+      expect(DiscourseTranslator::Base.text_for_detection(post)).to eq(cooked)
+    end
+
     it "truncates to DETECTION_CHAR_LIMIT of 1000" do
       post.cooked = "a" * 1001
       expect(DiscourseTranslator::Base.text_for_detection(post).length).to eq(1000)