# Posted Jim Weirich OSCON 2006 video presentation **URL:** \ **Category:** Ruby\ **Created:** [February 6, 2007, 10:15pm UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675 "2007-02-06T22:15:17Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Diego\_Scataglini](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3bc359/32.png) [@Diego\_Scataglini](https://www.ruby-forum.com/u/Diego_Scataglini)\ **Post date:** [February 6, 2007, 10:15pm UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675/1 "2007-02-06T22:15:17Z")
For anybody interested, I posted the talk about Design By Contract in Ruby that Jim W. gave @ OSCON 2006 on my blog. > **[Best Online Casino in Australia | Top Licensed Casinos for Gamblers](https://toponlinecasinoaustralia.com?anchor=jim_weirich_test_drivern_development)** > > Best Online Casino in Australia with licensed games only. Play blackjack, roulette, poker and other top-notch casino games. Enjoy gambling 24/7. I have 3 or 4 more that I am in the process of uploading. I am waiting for a written release from some of the presenters šŸ™‚ before I make them public. Last thing I need is to get sued šŸ˜ƒ Enjoy šŸ˜ƒ ---
**Author:** ![Diego\_Scataglini](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3bc359/32.png) [@Diego\_Scataglini](https://www.ruby-forum.com/u/Diego_Scataglini)\ **Post date:** [February 7, 2007, 12:19am UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675/2 "2007-02-07T00:19:31Z")
On Feb 6, 4:14 pm, ā€œDiego Scatagliniā€ [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > For anybody interested, I posted the talk about Design By Contract in Ruby > that Jim W. gave @ OSCON 2006 on my blog.[Best Online Casino in Australia | Top Licensed Casinos for Gamblers](http://jroller.com/page/dscataglini/?anchor=jim_weirich_test_drivern_)ā€¦ > > I have 3 or 4 more that I am in the process of uploading. > I am waiting for a written release from some of the presenters šŸ™‚ before I > make them public. > Last thing I need is to get sued šŸ˜ƒ Interesting presentation. The more these test/specification/dbc system evolve the more they seem like double-entry bookkeeping. Arenā€™t we just writing the code twice but from two differnt perspectives and seeing if they match up? T. ---
**Author:** ![Diego\_Scataglini](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3bc359/32.png) [@Diego\_Scataglini](https://www.ruby-forum.com/u/Diego_Scataglini)\ **Post date:** [February 7, 2007, 12:35am UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675/3 "2007-02-07T00:35:32Z")
Trans wrote: > The more these test/specification/dbc system evolve the more they seem > like double-entry bookkeeping. Arenā€™t we just writing the code twice > but from two differnt perspectives and seeing if they match up? > Mostly, yes. (Though usually the test is a drastic simplification for a > specific example.) Thrice if you do acceptance testing. Is that a bad > thing? Devin ---
**Author:** ![Diego\_Scataglini](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3bc359/32.png) [@Diego\_Scataglini](https://www.ruby-forum.com/u/Diego_Scataglini)\ **Post date:** [February 7, 2007, 6:29am UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675/4 "2007-02-07T06:29:51Z")
On Feb 6, 11:18 pm, ā€œDiego Scatagliniā€ [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I believe one of the main differences is that DBC is more of a runtime > check. Perhaps. But one of the first thing I thought when I saw Jim run it is whereā€™s the ā€œā€“debugā€? I donā€™t see why youā€™d want this to happen in production. T. ---
**Author:** ![Diego\_Scataglini](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3bc359/32.png) [@Diego\_Scataglini](https://www.ruby-forum.com/u/Diego_Scataglini)\ **Post date:** [February 7, 2007, 10:56am UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675/5 "2007-02-07T10:56:16Z")
On 7 Feb 2007, at 05:28, Trans wrote: > On Feb 6, 11:18 pm, ā€œDiego Scatagliniā€ [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > I believe one of the main differences is that DBC is more of a > > runtime > > check. > > Perhaps. But one of the first thing I thought when I saw Jim run it is > whereā€™s the ā€œā€“debugā€? I donā€™t see why youā€™d want this to happen in > production. Iā€™ve not watched the presentation, but with experience of other DBC systems I imagine the reason would be that contract violations can happen in production - and knowing about them is generally a good thing šŸ™‚ Cheers, Adrian ---
**Author:** ![Diego\_Scataglini](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3bc359/32.png) [@Diego\_Scataglini](https://www.ruby-forum.com/u/Diego_Scataglini)\ **Post date:** [February 8, 2007, 7:59pm UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675/6 "2007-02-08T19:59:55Z")
On Feb 6, 2007, at 6:18 PM, Trans wrote: > The more these test/specification/dbc system evolve the more they seem > like double-entry bookkeeping. Arenā€™t we just writing the code twice > but from two differnt perspectives and seeing if they match up? Given that double-entry bookkeeping is often cited as one of the subtle advancements that led to global the dominance of the Western world, Iā€™m not sure this is a bad thing. But. ā€œYes and noā€. For a single piece of code, itā€™s generally a lot simpler to test that the code did the right thing than to write the functional code itself. If you add in edge cases, the problem multiplies: itā€™s a lot easier to write 10 individual test cases, each for one edge case, than to write one piece of functional code that elegantly (or even inelegantly) handles all the edge cases. As your app grows, this aspect grows by leaps and bounds. Iā€™ve been asked something along the lines of ā€œwell how do we know that the test code doesnā€™t have bugs in it?ā€. The answer is that we donā€™t. However, think of this as a probability problem. The following are gross oversimplifications, but should get the gist. - If you have one test case per chunk of code, and that test case also has a 10% chance of being wrong, and if theyā€™re wrong in exactly the same way, then you have an 81% chance that the code executes correctly and tests cleanly, an 18% chance that the test fails (9% false positive, 9% false negative), and a 1% chance that the test passes incorrectly. Since a failure will likely to look through your code until you either find whatā€™s wrong in your code or your test, then youā€™ve just dramatically decreased the chance of an uncaught bug. - As code increases the likelyhood of bug-free code decreases exponentially with the amount of code. However, since tests often must implicitly test things other than the specific thing theyā€™re testing, the likelihood of bugs remaining uncaught also decreases at an exponential rate. There are limits to all of this, and I do think that people are prone to putting too much faith in automated testing, but it still runs circles around a lack of it. -faisal ---
**Author:** ![Diego\_Scataglini](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/3bc359/32.png) [@Diego\_Scataglini](https://www.ruby-forum.com/u/Diego_Scataglini)\ **Post date:** [February 7, 2007, 5:19am UTC](https://www.ruby-forum.com/t/posted-jim-weirich-oscon-2006-video-presentation/84675/7 "2007-02-07T05:19:46Z")
I believe one of the main differences is that DBC is more of a runtime check.