Remove line break after linking username mentions (#15788)

app/services/html/parser.rb

@@ -280,7 +280,7 @@ module Html
     def user_link_if_exists(mention)
       username = mention.delete("@").downcase
       if User.find_by(username: username)
-        <<~HTML
+        <<~HTML.chomp
           <a class='mentioned-user' href='#{ApplicationConfig['APP_PROTOCOL']}#{Settings::General.app_domain}/#{username}'>@#{username}</a>
         HTML
       else

spec/services/html/parser_spec.rb

@@ -400,6 +400,12 @@ RSpec.describe Html::Parser, type: :service do
       parsed_html = described_class.new(html).wrap_mentions_with_links.html
       expect(parsed_html).to include("<a")
     end
+
+    it "does not add an extra return" do
+      html = "@#{user.username}"
+      parsed_html = described_class.new(html).wrap_mentions_with_links.html
+      expect(parsed_html).not_to include("\n")
+    end
   end
 
   describe "#parse_emojis" do

spec/services/markdown_processor/parser_spec.rb

@@ -224,7 +224,7 @@ RSpec.describe MarkdownProcessor::Parser, type: :service do
       # rubocop:disable Layout/LineLength
       expected_result = "<p><code>@#{user.username}</code> one two, <a class=\"mentioned-user\" " \
                         "href=\"#{ApplicationConfig['APP_PROTOCOL']}#{ApplicationConfig['APP_DOMAIN']}/#{user.username}\">" \
-                        "@#{user.username}</a>\n three four:</p>\n\n<ul>\n<li><code>@#{user.username}</code></li>\n</ul>\n\n"
+                        "@#{user.username}</a> three four:</p>\n\n<ul>\n<li><code>@#{user.username}</code></li>\n</ul>\n\n"
       # rubocop:enable Layout/LineLength
       expect(result).to eq(expected_result)
     end