Unit testing an Activerecord domain model with NUnit

[Digression] This post has been sitting in a somewhat unfinished state for a long time. It feels good to finally post it!

In rewriting my baseball game, CSFBL, I made the decision to use Castle ActiveRecord (built on top of NHibernate) to handle the persistence of my domain model. As a result, I needed to find a simple but effective way to unit test this implementation.

The unit tests needed to accomplish the following:

  1. Test the initialization of ActiveRecord (which validates the database schema against the object mappings).
  2. Test object validation (since I am using Castle’s Validation component and the ActiveRecordValidationBase<T> base class).
  3. Ensure that a domain object can be persisted to the database.
  4. Ensure that a domain object can be retrieved from the database.
  5. Ensure that multiple instances of an object with the same persisted primary key are equal.

How, then, do we do this? Continue reading

ComputerSims Baseball: Powered by MonoRail and ActiveRecord

For the past seven years, I’ve been maintaining an online baseball game, CSFBL (Computer Simulated Fantasy Baseball League). It’s gone through many changes over the years, but its core is in many ways unchanged since 2002 — and therein lies a problem.

Back in 2002, CSFBL was getting about 50,000 to 100,000 page views per month. By the end of 2003, we were simulating about 1,500 games per day. Today, we get about 4 million page views per month, simulate up to 10,000 games per day, and have over 80GB of historical data (roughly 6 million games spanning 2,700 seasons). That’s significant growth — and the game is suffering as a result. It wasn’t built to scale this far – a victim of its own success and my own limitations as a programmer circa 2002.

I realized long ago that a rewrite from the ground-up was necessary. I’ve done extensive work rewriting the database schema to maximize efficiency, but that’s only part of it — I need to rewrite the web site and simulation engine as well. (They currently run on classic ASP and Visual Basic, respectively.)

Originally, the rewrite was going to use WebForms — but that changed when I found MonoRail. Up until two weeks ago, data access relied on Paul Wilson’s O/R Mapper (WORM) and WilsonORWrapper (WORW) — but I just completed the switch to ActiveRecord.

Why abandon WORM/WORW? Three reasons:

  1. I was concerned that I’d run into situations where I needed more power than WORM could provide.
  2. NHibernate and ActiveRecord have incredibly robust communities that dwarf those of the alternatives.
  3. I needed to pick my first ActiveRecord project. :)

I still think WORM/WORW are valid choices, but the scope of CSBB is potentially huge, and I knew I needed to follow the leader.

Converting to ActiveRecord was straightforward (one O/R mapper to another), but I did run into one frustrating problem. I had a problem persisting one ActiveRecord classes. Attempting to save it didn’t throw an exception; rather, it just sat there, as if in an endless loop. I traced the call to an NHibernate method call by ActiveRecord, but couldn’t figure out why it wouldn’t do anything. Turning on logging, I recognized the problem: one of my fields (a not null field in the database) wasn’t marked with the [Property] attribute, so it wasn’t included in the INSERT statement. Running the SQL code in MySQL Query Browser threw an error, but not in NHibernate. Frustrating, and possibly an issue with the MySQL provider for NHibernate, but at least I know what to look out for if I see a similar problem in the future.

Still, it feels good to be in the hands of MonoRail + ActiveRecord for the most significant independent, most rewarding, and most unpaid development project of my life. :)