expect (MiniTest::Mock)

    # File lib/minitest/mock.rb, line 10
        def expect(name, retval, args=[])
          n, r, a = name, retval, args # for the closure below
          @expected_calls[name] = { :retval => retval, :args => args }
          self.class.__send__(:define_method, name) { |*x|
            raise ArgumentError unless @expected_calls[n][:args].size == x.size
            @actual_calls[n] << { :retval => r, :args => x }
            retval
          }
          self
        end