5 files changed, 85 insertions, 11 deletions

diff --git a/rubocop/cop/activerecord_serialize.rb b/rubocop/cop/activerecord_serialize.rb
index bfa0cff9a67..9bdcc3b4c34 100644
--- a/rubocop/cop/activerecord_serialize.rb
+++ b/rubocop/cop/activerecord_serialize.rb
@@ -1,24 +1,18 @@
+require_relative '../model_helpers'
+
 module RuboCop
   module Cop
     # Cop that prevents the use of `serialize` in ActiveRecord models.
     class ActiverecordSerialize < RuboCop::Cop::Cop
+      include ModelHelpers
+
       MSG = 'Do not store serialized data in the database, use separate columns and/or tables instead'.freeze
 
       def on_send(node)
-        return unless in_models?(node)
+        return unless in_model?(node)
 
         add_offense(node, :selector) if node.children[1] == :serialize
       end
-
-      def models_path
-        File.join(Dir.pwd, 'app', 'models')
-      end
-
-      def in_models?(node)
-        path = node.location.expression.source_buffer.name
-
-        path.start_with?(models_path)
-      end
     end
   end
 end
diff --git a/rubocop/cop/polymorphic_associations.rb b/rubocop/cop/polymorphic_associations.rb
new file mode 100644
index 00000000000..7d554704550
--- /dev/null
+++ b/rubocop/cop/polymorphic_associations.rb
@@ -0,0 +1,23 @@
+require_relative '../model_helpers'
+
+module RuboCop
+  module Cop
+    # Cop that prevents the use of polymorphic associations
+    class PolymorphicAssociations < RuboCop::Cop::Cop
+      include ModelHelpers
+
+      MSG = 'Do not use polymorphic associations, use separate tables instead'.freeze
+
+      def on_send(node)
+        return unless in_model?(node)
+        return unless node.children[1] == :belongs_to
+
+        node.children.last.each_node(:pair) do |pair|
+          key_name = pair.children[0].children[0]
+
+          add_offense(pair, :expression) if key_name == :polymorphic
+        end
+      end
+    end
+  end
+end
diff --git a/rubocop/cop/redirect_with_status.rb b/rubocop/cop/redirect_with_status.rb
new file mode 100644
index 00000000000..36810642c88
--- /dev/null
+++ b/rubocop/cop/redirect_with_status.rb
@@ -0,0 +1,44 @@
+module RuboCop
+  module Cop
+    # This cop prevents usage of 'redirect_to' in actions 'destroy' without specifying 'status'.
+    # See https://gitlab.com/gitlab-org/gitlab-ce/issues/31840
+    class RedirectWithStatus < RuboCop::Cop::Cop
+      MSG = 'Do not use "redirect_to" without "status" in "destroy" action'.freeze
+
+      def on_def(node)
+        return unless in_controller?(node)
+        return unless destroy?(node) || destroy_all?(node)
+
+        node.each_descendant(:send) do |def_node|
+          next unless redirect_to?(def_node)
+
+          methods = []
+
+          def_node.children.last.each_node(:pair) do |pair|
+            methods << pair.children.first.children.first
+          end
+
+          add_offense(def_node, :selector) unless methods.include?(:status)
+        end
+      end
+
+      private
+
+      def in_controller?(node)
+        node.location.expression.source_buffer.name.end_with?('_controller.rb')
+      end
+
+      def destroy?(node)
+        node.children.first == :destroy
+      end
+
+      def destroy_all?(node)
+        node.children.first == :destroy_all
+      end
+
+      def redirect_to?(node)
+        node.children[1] == :redirect_to
+      end
+    end
+  end
+end
diff --git a/rubocop/model_helpers.rb b/rubocop/model_helpers.rb
new file mode 100644
index 00000000000..309723dc34c
--- /dev/null
+++ b/rubocop/model_helpers.rb
@@ -0,0 +1,11 @@
+module RuboCop
+  module ModelHelpers
+    # Returns true if the given node originated from the models directory.
+    def in_model?(node)
+      path = node.location.expression.source_buffer.name
+      models_path = File.join(Dir.pwd, 'app', 'models')
+
+      path.start_with?(models_path)
+    end
+  end
+end
diff --git a/rubocop/rubocop.rb b/rubocop/rubocop.rb
index 17d2bf6aa1c..dae30969abf 100644
--- a/rubocop/rubocop.rb
+++ b/rubocop/rubocop.rb
@@ -1,6 +1,8 @@
 require_relative 'cop/custom_error_class'
 require_relative 'cop/gem_fetcher'
 require_relative 'cop/activerecord_serialize'
+require_relative 'cop/redirect_with_status'
+require_relative 'cop/polymorphic_associations'
 require_relative 'cop/migration/add_column'
 require_relative 'cop/migration/add_column_with_default_to_large_table'
 require_relative 'cop/migration/add_concurrent_foreign_key'