what's diffrence between ({:these=>"params"}) and ({"these"

When i use rspec(with built-in mock framework) ,error occurs. I use rspec_scaffold generate a example as below:

      it "should expose a newly created awarding_body as @awarding_body" do         AwardingBody.should_receive(:new).with(:these                          =>'params').and_return(mock_awarding_body(:save => true))

         post :create, :awarding_body => {:these => 'params'}         assigns(:awarding_body).should == (mock_awarding_body)       end

After execute the example , a error occurs as below :

Mock 'Class' expected :new with ({:these=>"params"}) but received it with ({"the se"=>"params"})

Mock 'Class' expected :new with ({:these=>"params"}) but received it with ({"the se"=>"params"})

Probably because actioncontroller magics the params hash into a hash
with string keys, not symbol keys.

Fred