From: Jim Weirich <jweirich@...>
Date: 2003-06-05T21:32:02+09:00
Subject: Re: A unit testing problem...

On Thu, 2003-06-05 at 01:58, Hal E. Fulton wrote:

> But of course, interactive tests are not good in 
> the long term.

Agreed.

> How would you test this? For my first pass, I 
> didn't have to make any changes to my X10 class;
> I just substituted a fake SerialPort class.

I assume in your tests you can script the entire exchange.  In other
words, when you wish to test a scenario, you know exactly what you will
send and when repsonses you will get back.

If that's the case, you could do something like this ...

  def test_startup_protocol
    port = MockSerialPort.new(
      :put, 0x80, 0x81, 
      :get, 0x00, 0x01, 
      :put, 0xff)
    cm11a = CM11A.new(port)
    cm11a.startup
  end

The MockSerialPort object might look something like this ...

class MockSerialPort
  include Test::Unit::Assertions

  def initialize(*script)
    @mode = :put
    @script = script
  end

  def putc(byte)
    expected = get_next
    assert_equal :put, @mode
    assert_equal expected, byte, "while putting"
  end

  def getc
    expected = get_next
    assert_equal :get, @mode
    expected
  end

  def get_next
    while val = @script.shift
      case val
      when :put
	@mode = val
      when :get
	@mode = val
      when Integer
	return val
      when nil
	return val
      end
    end
  end
end



-- 
-- Jim Weirich       jweirich@one.net      http://onestepback.org
-----------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct, 
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)