91 allow includes strings (#93)

* add hash benchmarking to performance tests

* Add missing attribute in README example

* Disable GC before doing performance test

* Enable oj to AM for fair benchmark test

* add information on performance methodology

* add oss metadata

* Make an error that demonstrates [Issue

* Simple RSpec test that fails with a non-empty string but passes with a
non-empty symbol
* To run the test, rspec spec/lib/object_serializer_spec.rb

* Map includes to symbols if they are provided as strings

* Includes would fail with an ArgumentError unless they were explicitly
provided as symbols (see #97)
* This is solved by mapping the strings to symbols in the
ObjectSerializer initializer
* No real impact on performance here

lib/fast_jsonapi/object_serializer.rb

@@ -77,7 +77,17 @@ def process_options(options)
 
       if options[:include].present?
         @includes = options[:include].delete_if(&:blank?).map(&:to_sym)
-        self.class.validate_includes!(@includes)
+        validate_includes!(@includes)
+      end
+    end
+
+    def validate_includes!(includes)
+      return if includes.blank?
+
+      existing_relationships = self.class.relationships_to_serialize.keys.to_set
+
+      unless existing_relationships.superset?(includes.to_set)
+        raise ArgumentError, "One of keys from #{includes} is not specified as a relationship on the serializer"
       end
     end
 

spec/lib/object_serializer_performance_spec.rb

@@ -33,6 +33,9 @@
     }
   }
 
+  before(:all) { GC.disable }
+  after(:all) { GC.enable }
+
   context 'when testing performance of serialization' do
     it 'should create a hash of 1000 records in less than 50 ms' do
       movies = 1000.times.map { |_i| movie }