Subclass TaskList::Filter to fix a bugrs-issue-1645

Instead of using a fork, we subclass the filter and only apply the
`task-list` class to list items that actually are task lists.

Closes #1645

See https://github.com/github/task_list/pull/60

2 files changed, 25 insertions, 2 deletions

diff --git a/lib/gitlab/markdown.rb b/lib/gitlab/markdown.rb
index 133010adcaf..c0fb22e7f36 100644
--- a/lib/gitlab/markdown.rb
+++ b/lib/gitlab/markdown.rb
@@ -1,5 +1,4 @@
 require 'html/pipeline'
-require 'task_list/filter'
 
 module Gitlab
   # Custom parser for GitLab-flavored Markdown
@@ -19,6 +18,7 @@ module Gitlab
     autoload :SanitizationFilter,           'gitlab/markdown/sanitization_filter'
     autoload :SnippetReferenceFilter,       'gitlab/markdown/snippet_reference_filter'
     autoload :TableOfContentsFilter,        'gitlab/markdown/table_of_contents_filter'
+    autoload :TaskListFilter,               'gitlab/markdown/task_list_filter'
     autoload :UserReferenceFilter,          'gitlab/markdown/user_reference_filter'
 
     # Public: Parse the provided text with GitLab-Flavored Markdown
@@ -113,7 +113,7 @@ module Gitlab
         Gitlab::Markdown::CommitReferenceFilter,
         Gitlab::Markdown::LabelReferenceFilter,
 
-        TaskList::Filter
+        Gitlab::Markdown::TaskListFilter
       ]
     end
   end
diff --git a/lib/gitlab/markdown/task_list_filter.rb b/lib/gitlab/markdown/task_list_filter.rb
new file mode 100644
index 00000000000..c6eb2e2bf6d
--- /dev/null
+++ b/lib/gitlab/markdown/task_list_filter.rb
@@ -0,0 +1,23 @@
+require 'task_list/filter'
+
+module Gitlab
+  module Markdown
+    # Work around a bug in the default TaskList::Filter that adds a `task-list`
+    # class to every list element, regardless of whether or not it contains a
+    # task list.
+    #
+    # This is a (hopefully) temporary fix, pending a new release of the
+    # task_list gem.
+    #
+    # See https://github.com/github/task_list/pull/60
+    class TaskListFilter < TaskList::Filter
+      def add_css_class(node, *new_class_names)
+        if new_class_names.include?('task-list')
+          super if node.children.any? { |c| c['class'] == 'task-list-item' }
+        else
+          super
+        end
+      end
+    end
+  end
+end