Relation#explain no longer returns a string, but a Relation::ExplainP…

…roxy. Calling #inspect will return the string, and is backwards compatible.

spec/awesome_nested_set_spec.rb

@@ -1225,13 +1225,13 @@ def check_structure(entries, structure)
     it "should sort by custom sort column" do
       expect(OrderedCategory.acts_as_nested_set_options[:order_column]).to eq('name')
       expect(OrderedCategory.order_column_name).to eq('name')
-      expect(OrderedCategory.first.children.explain).to include('ORDER BY name')
+      expect(OrderedCategory.first.children.explain.inspect).to include('ORDER BY name')
     end
 
     it "should sort by custom hash sort" do
       expect(HashOrderedCategory.acts_as_nested_set_options[:order_column]).to eq({ :name => :desc })
       expect(HashOrderedCategory.order_column_name).to eq({ :name => :desc })
-      expect(HashOrderedCategory.first.children.explain).to include(
+      expect(HashOrderedCategory.first.children.explain.inspect).to include(
         "ORDER BY #{HashOrderedCategory.quoted_table_name}.#{HashOrderedCategory.connection.quote_column_name(:name)} DESC"
       )
     end