Fix leading slash in redirects and add cop

2 files changed, 53 insertions, 0 deletions

diff --git a/rubocop/cop/avoid_route_redirect_leading_slash.rb b/rubocop/cop/avoid_route_redirect_leading_slash.rb
new file mode 100644
index 00000000000..7ac1c881269
--- /dev/null
+++ b/rubocop/cop/avoid_route_redirect_leading_slash.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    # Checks for a leading '/' in route redirects
+    # For more information see: https://gitlab.com/gitlab-org/gitlab-ce/issues/50645
+    #
+    # @example
+    #   # bad
+    #   root to: redirect('/-/instance/statistics/conversational_development_index')
+    #
+    #   # good
+    #   root to: redirect('-/instance/statistics/conversational_development_index')
+    #
+
+    class AvoidRouteRedirectLeadingSlash < RuboCop::Cop::Cop
+      MSG = 'Do not use a leading "/" in route redirects'
+
+      def_node_matcher :leading_slash_in_redirect?, <<~PATTERN
+        (send nil? :redirect (str #has_leading_slash?))
+      PATTERN
+
+      def on_send(node)
+        return unless in_routes?(node)
+        return unless leading_slash_in_redirect?(node)
+
+        add_offense(node)
+      end
+
+      def has_leading_slash?(str)
+        str.start_with?("/")
+      end
+
+      def in_routes?(node)
+        path = node.location.expression.source_buffer.name
+        dirname = File.dirname(path)
+        filename = File.basename(path)
+        dirname.end_with?('config/routes') || filename.end_with?('routes.rb')
+      end
+
+      def autocorrect(node)
+        lambda do |corrector|
+          corrector.replace(node.loc.expression, remove_leading_slash(node))
+        end
+      end
+
+      def remove_leading_slash(node)
+        node.source.sub('/', '')
+      end
+    end
+  end
+end
diff --git a/rubocop/rubocop.rb b/rubocop/rubocop.rb
index 9d6cc73fc3b..ff929c7b6ce 100644
--- a/rubocop/rubocop.rb
+++ b/rubocop/rubocop.rb
@@ -7,6 +7,7 @@ require_relative 'cop/gitlab/union'
 require_relative 'cop/include_sidekiq_worker'
 require_relative 'cop/avoid_return_from_blocks'
 require_relative 'cop/avoid_break_from_strong_memoize'
+require_relative 'cop/avoid_route_redirect_leading_slash'
 require_relative 'cop/line_break_around_conditional_block'
 require_relative 'cop/prefer_class_methods_over_module'
 require_relative 'cop/migration/add_column'