Vinod Kurup

Hospitalist/programmer in search of the meaning of life

May 16, 2006 - 3 minute read - Comments - programming tcl testing openacs

Automated Testing Rules

Automated testing is a good thing. For my running log application, I have a proc that creates a new log for a user, called rl::runner::new. If you happen to call it for a user who already has a log, it returns the already created log. When I created the proc way back when, I also created an automated test to make sure that creation worked and that redundant calls returned the orignal log.

Over time, I added some code to make sure that users are given proper permissions on their log. Anytime you make a change, you should run your tests, but of course, I didn’t :-) Well, today I did and my test now failed.

Here is the relevant (edited) code:

set runner_id [db_nextval acs_object_id_seq] 
set ret_val [db_exec_plsql new_runner {}]
permission::grant -party_id $user_id -object_id $runner_id -privilege admin
permission::grant -party_id $user_id -object_id $runner_id -privilege write

The error was happening in permission::grant. It was complaining that $runner_id wasn’t a valid acs_object. What’s going on? It looks like it should work. The problem is that I should be granting the permission on ret_val, not on runner_id. (Probably a bad choice of variable names). The first time a log is created, db_exec_plsql returns a value which happens to be the same as runner_id. The second time it’s called, it returns a value which is different and permission::grant fails.

I would never have caught this error until I tried to call rl::runner::new the second time on the same user. Which would make it one of those very difficult to track bugs. Automated testing saved me a lot of annoying debugging.

That said, I wish OpenACS’s testing facilities were better. I worked on a couple other bugs today and I’m trying really hard to write tests to expose bugs before fixing them, but it’s really a strain. Especially when you need to do a combination of black box and white box testing. I’d like to make testing easier in OpenACS, but I’m not sure if I have the brainpower :-)

Comments from old site

Improving Testing


There is definitely room for improvement. You can specify test dependency, I think, so you can create a test package environment, then run several tests using that setup. I haven't tried that yet, but it should help.

Anothing thing to keep in mind is that testing can expose places in your code that might need to be decoupled. That is one of the advantages of testing, by thinking of how to run the code is isolation in the test, you can discover a better design :)

Dave Bauer 2006-05-17 07:27:51

New Features coming in Tcl 8.5 Doc on Board

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