Test to check if the data-attr if nil is same or not

if data attribute is nil it is ignored

if value is nil the pair is ignored

if value is nil it is skipped

Improved test for  data attr nil

actionview/lib/action_view/helpers/tag_helper.rb

@@ -154,6 +154,7 @@ module ActionView
           options.each_pair do |key, value|
             if TAG_PREFIXES.include?(key) && value.is_a?(Hash)
               value.each_pair do |k, v|
+                next if v.nil?
                 output << sep
                 output << prefix_tag_option(key, k, v, escape)
               end

actionview/test/template/tag_helper_test.rb

@@ -173,4 +173,10 @@ class TagHelperTest < ActionView::TestCase
         tag('a', { aria => { a_float: 3.14, a_big_decimal: BigDecimal.new("-123.456"), a_number: 1, string: 'hello', symbol: :foo, array: [1, 2, 3], hash: { key: 'value'}, string_with_quotes: 'double"quote"party"' } })
     }
   end
+
+  def test_link_to_data_nil_equal
+    div_type1 = content_tag(:div, 'test', { 'data-tooltip' => nil })
+    div_type2 = content_tag(:div, 'test', { data: {tooltip: nil} })
+    assert_dom_equal div_type1, div_type2 
+  end
 end