HCoder.org

Slides for several talks now published

I had said that I was going to publish the slides for a couple of talks I had given over the last couple of months, and I just got around to actually do it, so here they are:

• Software automated testing 123, an entry-level talk about software automated testing. Why you should be doing it (if you’re not already), some advice for test writing, some basic concepts and some basic examples (in Perl, but I trust it shouldn’t be too hard to follow even if you don’t know the language).

• Taming the Snake: Python unit tests, another entry-level talk, but this time about Python unit testing specifically. How to write xUnit style tests with unittest, some advice and conventions and some notes on how to use the excellent nosetests tool.

• Introduction to Debian packaging, divided in four sessions: Introduction, Packaging a simple app, Backporting software and Packaging tools.

Just a quick note about them: the slides shouldn’t be too hard to understand without me talking, but of course you’ll lose some stuff that is not written down, some twists, clarifications of what I mean exactly by different things and whatnot. In particular, the “They. don’t. make. sense. Don’t. write. them” stuff refers to tests that don’t have a reliable/controlled environment to run into. I feel really strong about them, so I wanted to dedicate a few more seconds to smashing the idea that they’re ok, hence the extra slides :-)

Enjoy them, and please send me any comments you have about them!

• automated
• courses
• Debian
• packaging
• python
• slides
• talks
• testing
• tests

BCM4312 on Linux: easier than expected

Just a quick post to say that I was being stupid and it took me a couple of days of fighting, lockups and reading to realise that the driver for the wireless card in my new laptop is actually already packaged and it works like a charm.

The long(er) story:

• I bought a laptop with that card, and I wanted to make it work.

• Apparently the open source driver (b43) doesn’t recognise my card, although it seems it should?

• I tried to download the proprietary driver provided by the vendor (wl), but it didn’t compile at first. After applying some patch for the kernel 2.6.29 (I’m using kernel 2.6.30) it did compile, but it didn’t quite work. Meaning, it locked up my machine seconds after loading.

• After a couple of days of wondering and trying to make it work… I realised the driver is already compiled in Debian (in particular, broadcom-sta-modules-2.6.30-1-686). Just installing and loading it worked like a charm. Oh well.

• bcm
• bcm4312
• broadcom
• card
• Debian
• packages
• problems
• wireless
• wl

My first contributions to CPAN

I have been using Perl for many years, but I had never uploaded anything to CPAN. That’s unfortunate, because I’ve probably written several programs or modules that could have been useful for other people. The point is, now I have. Not only that, but it was code I wrote at work, so if I’m not mistaken these are my first contributions to free software from Opera. Yay me!

The two modules I’ve released so far are:

• Parse::Debian::PackageDesc, a module for parsing both .dsc and .changes files from Debian. This is actually a support module for something bigger that I hope I’ll release soon-ish.

• Migraine, a still somewhat primitive database change manager inspired on the Ruby on Rails migration system.

As I feel that Migraine could be useful to a lot of people, but it’s easy to misunderstand what it really does (unless you already know Rails migrations of course), I’ll elaborate a bit. Imagine that you are developing some application that uses a database. You design the schema, write some SQL file with it, and everybody creates their own databases from that file. Now, as your application evolves, your schema will evolve too. What do you do now to update all databases (every developer installation, testing installations, and don’t forget the production database)? One painful way to do it could be documenting which SQL statements you have to execute in order to have the latest version of the schema, and expect people to apply copying-and-pasting from the documentation. However, it’s messy, confusing, and it needs someone to know both which databases to update and when.

Migraine offers a simpler, more reliable way to keep all your databases up to date. Basically, you write all your changes (“migrations”) in some files in a directory, following a simple version number naming convention (e.g. 001-add_users_table.sql, 002-change_passwd_field_type.sql), and migraine will allow you to keep your databases up to date. In the simplest, most common case, you call migraine with a configuration file specifying which database to upgrade, and it will figure out which migrations are pending to apply, if any, and apply them. The system currently only supports raw SQL, but it should be easy to extend with other types.

In principle, you shouldn’t need to write any Perl code to use migraine (it has a Perl module that you can use to integrate with your Perl programs if you like, but also a command-line tool), so you can use it even in non-Perl projects. Of course, some modern ORMs have their own database migration system, but very often you have to maintain legacy code that doesn’t use any fancy ORM, or you don’t like the migration system provided by the ORM, or you prefer keeping a single system for schema and data migrations… I think in those cases Migraine can help a lot reducing chaos and keeping things under control. Try it out and tell me what you think :-)

In a couple of days I’ll blog again about other contributions to free software I’ve made lately, but this time in the form of Opera widgets…

• bsd
• cpan
• databases
• Debian
• free
• migraine
• migration
• parsing
• perl
• software

Free software rocks!

I’ve been working on something lately that I hope I will publish sometime next month: it’s a set of tools to manage an APT package repository. The idea is that, given an upload queue (you can set it up as an anonymous FTP, or some directory accessible via SSH/SCP, or whatever floats your boat in your setup and team), you’ll have a web interface to approve those packages, a set of integrated autobuilders building the approved packages in whatever combination of architectures and distributions you want, and all that integrated with reprepro to keep your repository updated. I’ll write more about it when I have released something.

The point now is that, while working on it, I needed some module to parse command-line options and “subcommands” (like git commit, svn update, etc.). As it’s written in Perl, I had a look at CPAN to see if I could see anything. The most promising module was App::Rad, but it lacked a couple of things that were very important for me: my idea was “declaring” all the possible commands and options and have the module do all the work for me (generating the help pages and the default --help implementation, generate the program help subcommand and so on). App::Rad didn’t have that, and it didn’t seem to me like that was the direction they wanted to go to with the module. But I figured I’d drop the author an e-mail anyway and see if he liked the idea so I could start adding support for all that…

And boy was that a good idea. He replied a couple of days later, and said that they had liked the idea so much that they had implemented it already (that’s why he took a couple of days to reply), and he sent me an example of the new syntax they had introduced and asked if that was what I was thinking. And not only that, but they added me to the list of contributors just for giving the idea! That completely made my day, free software rocks!

• apt
• command
• cpan
• Debian
• free
• line
• perl
• projects
• software