Added Cop to blacklist the use of serialize

This Cop blacklists the use of ActiveRecord's "serialize" method, except
for cases where we already use this.

2 files changed, 25 insertions, 0 deletions

diff --git a/rubocop/cop/activerecord_serialize.rb b/rubocop/cop/activerecord_serialize.rb
new file mode 100644
index 00000000000..bfa0cff9a67
--- /dev/null
+++ b/rubocop/cop/activerecord_serialize.rb
@@ -0,0 +1,24 @@
+module RuboCop
+  module Cop
+    # Cop that prevents the use of `serialize` in ActiveRecord models.
+    class ActiverecordSerialize < RuboCop::Cop::Cop
+      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)
+
+        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/rubocop.rb b/rubocop/rubocop.rb
index b65efbc41f4..17d2bf6aa1c 100644
--- a/rubocop/rubocop.rb
+++ b/rubocop/rubocop.rb
@@ -1,5 +1,6 @@
 require_relative 'cop/custom_error_class'
 require_relative 'cop/gem_fetcher'
+require_relative 'cop/activerecord_serialize'
 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'