launchpad-dev team mailing list archive

[Barry Warsaw <barry@xxxxxxxxxxxxx>]

On Oct 8, 2009, at 7:34 AM, Gary Poster wrote:

> Therefore, I think that the "test what you fly, fly what you test"  
> axiom should be followed as a rule, unless there are really  
> compelling reasons not to.  A few additional dependencies are  
> generally worth it to me for the additional confidence in my releases.

As a general principle, I agree.  I think that the few additional  
dependencies you'll get because of your tests will be far outweighed  
by your package's run time dependencies (if you're anything like  
lazr.restful :).  Seriously though, distributing a fully self- 
contained and self-testable piece of software improves user confidence  
in the code for a small price of bandwidth and disk space.  And even  
those can be amortized in a typical application if the test  
dependencies are shared among packages.

> I do think that there is a subjective point at which the benefit  
> outweighs the cost.  I probably start to feel that I can break the  
> rule for library packages when the test dependencies are hard to  
> build or have a count of more than five or six.  On the other hand,  
> I pretty much never want to break the rule for deployments of  
> production systems.  In other words, if lazr.authentication started  
> getting really bloated because of test dependencies, I would be  
> tempted to break the rule for its release, and separate out the test  
> dependencies; contrariwise, if Launchpad got a lot of test  
> dependencies, I would not be tempted at all to break the rule for  
> its deployment.

I agree that there can be exceptions, but let's evaluate them on a  
case-by-case basis.

> Perhaps this is worth a reviewers' meeting discussion, or maybe we  
> can reach consensus on the list.

Feel free to add it to the agenda for tomorrow.
-Barry

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