Autolinking is more robust

and handles URLs with CGI params, recognizes more (and multiple)
trailing punctuation marks including entity-encoded punctuation like
`"`.

app/helpers/html_helper.rb

@@ -1,6 +1,9 @@
 module HtmlHelper
   include ERB::Util
 
+  EXCLUDE_PUNCTUATION = %(.?,:!;"'<>)
+  EXCLUDE_PUNCTUATION_REGEX = /[#{Regexp.escape(EXCLUDE_PUNCTUATION)}]+\z/
+
   def format_html(html)
     fragment = Nokogiri::HTML5.fragment(html)
 
@@ -44,8 +47,10 @@ module HtmlHelper
     end
 
     def extract_url_and_punctuation(url_match)
-      if url_match.end_with?(".", "?", ",", ":")
-        [ url_match[..-2], url_match[-1] ]
+      url_match = CGI.unescapeHTML(url_match)
+      if match = url_match.match(EXCLUDE_PUNCTUATION_REGEX)
+        len = match[0].length
+        [ url_match[..-(len+1)], url_match[-len..] ]
       else
         [ url_match, "" ]
       end

test/helpers/html_helper_test.rb

@@ -10,25 +10,65 @@ class HtmlHelperTest < ActionView::TestCase
       format_html("<p>Check this: https://example.com/</p>")
   end
 
-  test "don't' include punctuation in URL autolinking" do
+  test "don't include punctuation in URL autolinking" do
     assert_equal_html \
-      %(<p>Check this: <a href="https://example.com" rel="noreferrer">https://example.com</a>!</p>),
-      format_html("<p>Check this: https://example.com!</p>")
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>!</p>),
+      format_html("<p>Check this: https://example.com/!</p>")
     assert_equal_html \
-      %(<p>Check this: <a href="https://example.com" rel="noreferrer">https://example.com</a>.</p>),
-      format_html("<p>Check this: https://example.com.</p>")
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>.</p>),
+      format_html("<p>Check this: https://example.com/.</p>")
     assert_equal_html \
-      %(<p>Check this: <a href="https://example.com" rel="noreferrer">https://example.com</a>?</p>),
-      format_html("<p>Check this: https://example.com?</p>")
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>?</p>),
+      format_html("<p>Check this: https://example.com/?</p>")
     assert_equal_html \
-      %(<p>Check this: <a href="https://example.com" rel="noreferrer">https://example.com</a>,</p>),
-      format_html("<p>Check this: https://example.com,</p>")
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>,</p>),
+      format_html("<p>Check this: https://example.com/,</p>")
     assert_equal_html \
-      %(<p>Check this: <a href="https://example.com" rel="noreferrer">https://example.com</a>:</p>),
-      format_html("<p>Check this: https://example.com:</p>")
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>:</p>),
+      format_html("<p>Check this: https://example.com/:</p>")
     assert_equal_html \
-      %(<p>Check this: <a href="https://example.com" rel="noreferrer">https://example.com</a>;</p>),
-      format_html("<p>Check this: https://example.com;</p>")
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>;</p>),
+      format_html("<p>Check this: https://example.com/;</p>")
+    assert_equal_html \
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>"</p>),
+      format_html("<p>Check this: https://example.com/\"</p>")
+    assert_equal_html \
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>'</p>),
+      format_html("<p>Check this: https://example.com/'</p>")
+
+    # trailing entities that decode to punctuation
+    # use assert_equal and not assert_equal_html to make sure we're getting entities correct
+    assert_equal \
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>&lt;</p>),
+      format_html("<p>Check this: https://example.com/&lt;</p>")
+    assert_equal \
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>&gt;</p>),
+      format_html("<p>Check this: https://example.com/&gt;</p>")
+    assert_equal \
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>"</p>),
+      format_html("<p>Check this: https://example.com/&quot;</p>")
+
+    # multiple punctuation characters including entities
+    assert_equal_html \
+      %(<p>Check this: <a href="https://example.com/" rel="noreferrer">https://example.com/</a>!?;</p>),
+      format_html("<p>Check this: https://example.com/!?;</p>")
+    assert_equal_html \
+      %(&lt;img src="<a href="https://example.com/" rel="noreferrer">https://example.com/</a>"&gt;),
+      format_html(%(&lt;img src=&quot;https://example.com/&quot;&gt;))
+    assert_equal_html \
+      %(&lt;img src="<a href="https://example.com/" rel="noreferrer">https://example.com/</a>"!&gt;),
+      format_html(%(&lt;img src=&quot;https://example.com/&quot;!&gt;))
+  end
+
+  test "handle URLs with query parameters" do
+    # use assert_equal and not assert_equal_html to make sure we're getting entities correct
+    assert_equal \
+      %(<p>Check this: <a href="https://example.com/a?b=c&amp;d=e" rel="noreferrer">https://example.com/a?b=c&amp;d=e</a></p>),
+      format_html("<p>Check this: https://example.com/a?b=c&amp;d=e</p>")
+
+    assert_equal \
+      %(<p>Check this: <a href="https://example.com/a?b=c&amp;d=e" rel="noreferrer">https://example.com/a?b=c&amp;d=e</a></p>),
+      format_html("<p>Check this: https://example.com/a?b=c&d=e</p>")
   end
 
   test "respect existing links" do