spec: serialize objects for MemoryStore and NilStore

to catch problems when using a "real" cache in dev/prod

Change-Id: Ic9ed6bc0420e3435d49ac0be756ba66a6f3cb0f2
Reviewed-on: https://gerrit.instructure.com/25217
Reviewed-by: Brian Palmer <brianp@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

spec/mocha_extensions.rb

@@ -37,6 +37,15 @@ class ActiveRecord::Base
   def self.add_any_instantiation(ar_obj)
     raise(ArgumentError, "need to save first") if ar_obj.new_record?
     @@any_instantiation[ [ar_obj.class.base_ar_class, ar_obj.id] ] = ar_obj
+    # calling any_instantiation is likely to be because you're stubbing it,
+    # and to later be cached inadvertently from code that *thinks* it
+    # has a non-stubbed object. So let it dump, but not load (i.e.
+    # the MemoryStore and NilStore dumps that are just for testing,
+    # but just discard the result of dump)
+    def ar_obj.marshal_dump
+      nil
+    end
+    # no marshal_load; will raise an exception on load
     ar_obj
   end
 

spec/spec_helper.rb

@@ -126,6 +126,46 @@ class ActiveRecord::ConnectionAdapters::MysqlAdapter < ActiveRecord::ConnectionA
   end
 end
 
+
+# Be sure to actually test serializing things to non-existent caches,
+# but give Mocks a pass, since they won't exist in dev/prod
+Mocha::Mock.class_eval do
+  def marshal_dump
+    nil
+  end
+
+  def marshal_load(data)
+    raise "Mocks aren't really serializeable!"
+  end
+
+  def respond_to_with_marshalling?(symbol, include_private = false)
+    return true if [:marshal_dump, :marshal_load].include?(symbol)
+    respond_to_without_marshalling?(symbol, include_private)
+  end
+  alias_method_chain :respond_to?, :marshalling
+end
+
+[ActiveSupport::Cache::MemoryStore, NilStore].each do |store|
+  store.class_eval do
+    def write_with_serialization_check(name, value, options = nil)
+      Marshal.dump(value)
+      write_without_serialization_check(name, value, options)
+    end
+    alias_method_chain :write, :serialization_check
+  end
+end
+
+unless CANVAS_RAILS2
+  NilStore.class_eval do
+    def fetch_with_serialization_check(name, options = {}, &block)
+      result = fetch_without_serialization_check(name, options, &block)
+      Marshal.dump(result) if result
+      result
+    end
+    alias_method_chain :fetch, :serialization_check
+  end
+end
+
 Spec::Matchers.define :encompass do |expected|
   match do |actual|
     if expected.is_a?(Array) && actual.is_a?(Array)