invoke_return_block (Spec::Mocks::BaseExpectation)

    # File lib/spec/mocks/message_expectation.rb, line 135
          def invoke_return_block(*args, &block)
            args << block unless block.nil?
            # Ruby 1.9 - when we set @return_block to return values
            # regardless of arguments, any arguments will result in
            # a "wrong number of arguments" error
            @return_block.arity == 0 ? @return_block.call : @return_block.call(*args)
          end