[Pharo-project] Good reference on time on unit testing?

Norbert Hartl norbert at hartl.name
Sun Feb 27 20:51:29 CET 2011

On 27.02.2011, at 13:58, Schwab,Wilhelm K wrote:

> Norbert,
> Excellent points - I take exception with only one: you assume that all developers test - that is sadly not true.  I am involved with a group who seem to think that a handful of tests added at the last minute will somehow magically fix their problems.  
It seems I wasn't clear on this one. I'm trying to making a point that there is no distinction between "testing" - "no testing" but between "testing" - "writing tests". If you take compilation you test the code for syntax and language quirks. If a developer runs the program he develops than he is testing already. Testing and running a program is the same form that point of view. He takes input parameter and expects output parameter. That is testing. The point is just that developers do it manually and that is not reproducable. So there is no real difference between manual testing all the time and written test case. Only that repeating the testing procedure is boring and therefor supposed to be done by a machine. So if developers could see that the just need to put the work they already doing into a test will ease the work without changing much. They are just changing style and save time. That's it. Talking about 100% test coverage and holistic views about what the perfect testing could be doesn't help.

> I have no problem arguing that testing (if done well) can/will reduce overall development time; the question is how much of that time one should expect to devote to writing and maintaining unit and acceptance tests?
I understand your intention but the view is inapropriate. Coding and testing aren't two things. It is something that belongs together (if you changed coding style). So that's why it is hard to estimate a time that should be spent. To me it is more comparabale to this: We all know collections are great. Imagine someone asking you "Can anyone recommend a good reference on the amount of time one should expect to spend writing code that uses collections?". What would you say? There is no answer. That doesn't mean you can't solve the problem. But you won't solving it by saying "It is 38.345 % of the time". If people don't get it you have to convince and/or teach them. I had several times where I could show the developer that he is gaining time from doing it. That works. Everything else is targeted towards excel manipulators.


> ________________________________________
> From: pharo-project-bounces at lists.gforge.inria.fr [pharo-project-bounces at lists.gforge.inria.fr] On Behalf Of Norbert Hartl [norbert at hartl.name]
> Sent: Sunday, February 27, 2011 5:41 AM
> To: Pharo-project at lists.gforge.inria.fr
> Subject: Re: [Pharo-project] Good reference on time on unit testing?
> Hi,
> On 27.02.2011, at 04:52, Schwab,Wilhelm K wrote:
>> Hello all,
>> Can anyone recommend a good reference on the amount of time one should expect to spend writing tests?  I will have to be the messenger (will be wearing running shoes just in case...), but I want the message to come from a solid source.
> I find that really hard to answer. To me the problem is the question itself. I heard the "..amount of time one should expect to spend writing tests?" so often in companies and I think it was always exactly this phrase. While the question is valid it gives the impression there is something that decucts time from your "normal" development work. So the people that are asking this question are often managing people that have read something about code quality and they want to apply _this_ to their teams.
> The definition over time is troublesome, too. Testing is not easy. Everything you read about testing gives you the impression that everyone knows how to test and that those developers are just too lazy. And that is not true. Most developers I met had problems to see what testing is all about. The don't see interfaces as provable promises etc. So if you tell any of these developers they should spend 1 hour a day in testing than you will get tests that are counter-productive. My favorite example is the one where you have any composite object with an add method. Than the test goes like adding something via the interface and then try to access the internal array and check if it is of size 1. To me it is the same as with documentation. I prefer to have less documentation than useless documentation.
> So every developer is testing in some way. You either test and debug on the way in an unstructured form or you write tests. To me writing tests is not an add-on it is a change in working style. From this point of view I would state that the time I need to spend _additionally_ for testing is negative.  I grew up with a print statement being the ultimate debugging tool. A print/debugging statement is added at the time of debugging and probably removed if the error seems to be fixed. That can lead to a situation where you do this multiple times. Writing the same as a test (and that forces you to produce more fine grained code) you will have a saving in time and a little assurance about regression. Regression debugging (debugging it again later) is much more time spent because you have to fix the error _and_ you need to focus again on that problem (which takes most of the time). So the point in writing tests is not to spend time but to save time.
> The amount of time one should expect to spend writing tests is less than the time you need to spend for testing otherwise. :)
> Norbert

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