Month: October 2007

I came across this post about debuggers today. I found it a lot more nuanced than the Giles Bowkett post on the same topic. The part of the post I found the most useful was when he used the issue of problems in production to advocate for two practices I’m a big fan of: test-driven development and effective logging.

I’m responsible for an app that wasn’t developed using TDD and had no logging at all when I first inherited it. When there were problems in production, we endured all manner of suffering to determine the causes and fix them. Once we added some unit tests and implemented logging in key locations (global.asax and catch blocks primarily), the number of issues we had dropped off significantly. And when there were issues, the log helped us diagnose and resolve problems far more quickly.

The other benefit of effective logging is to customer service. Once I made the contents available to a business analyst, she could see in real-time what was happening with the application and provide help to users more quickly too.

Whether you add it on after the fact or design it in from the beginning, logging is a must-have for today’s applications.

Buried deep in this Giles Bowkett post is the following gem:

“Tests are absolutely not for checking to see if things went wrong. They are for articulating what code should do, and proving that code does it.”

While it comes in the midst of an anti-debugger post (and an extended explanation of why comments on the post are closed), it is an excellent and concise statement of the purpose of unit tests.  It explains perhaps better than anything else I’ve read the main reason unit tests (or specifications, as the author would call them) should be written before the code.

If you use strongly-typed datasets in .NET, you’ve encountered the dreaded “Failed to enable constraints …” message.  I most recently encountered it this morning, while unit testing some new code.  There were far fewer search results for the phrase than I expected, so I’ll add my experience to the lot.

The XSD I’m working with has one table and one stored procedure with four parameters.  A call of this stored procedure (via a method in a business logic class) returns a one-column one-row result set.  My code threw a ConstraintException each time the result set value was zero (0).  To eliminate this problem, I changed the value of AllowDBNull attribute of each column in the XSD table from False to True (if the value wasn’t True already).  When I ran the unit tests again, they were successful.

I’ll have to research this further at some point, but I think part of the reason for ConstraintException being thrown in my case was the difference between the stored procedure’s result set columns and the table definition of the associated table adapter.

In any case, setting AllowDBNull to True is one way to eliminate that pesky error.

This Roy Osherove post surprised me because I hadn’t been aware of so many different interpretations of the idea before. Because I’ve always believed in at least some design up front, my understanding of TDD was the first of four mentioned:

“Test Driven Development: the idea of writing your code in a test first manner. You may already have an existing design in place.”

The fourth interpretation of TDD applies pretty well to what I do now whenever I inherit an application.  Writing unit tests of the middle tier(s) of the application (if none exist) has proven to be very helpful whenever I’ve done this.  Adding new features becomes easier, and regression testing becomes much easier.

This entertaining Phil Haack post on inherited code definitely tells the truth when it says:

“Here’s the dirty little secret about being a software developer. No matter how good the code you write is, it’s crap to another developer.”

Until I read this post, I hadn’t even thought about the thousands of lines of code I’ve left behind at various employers and how my successors regarded them.  I remember getting very positive feedback from a colleague who wrote the .NET replacement for my VB6/COM+/SQL Server 2000 implementation of our online recruitment tool, but that’s it.  My usual reaction to code I’ve inherited has rarely been empathetic.  Phil’s right in trying to be more understanding.
And to anyone who has inherited my code in the past, I hope I didn’t make your job too hard.

I’d forgotten this when writing a stored procedure to provide access to log entries in a database table.  This older post describes the problem, and two options for fixing it.  I chose the version that uses the DATEADD() function call for my stored procedure.

Earlier today, I came across this excellent post by Reginald Braithwaite on the management of software development.  It does a great job of explaining many of the projects I’ve worked on in my career, whether they succeeded or not.  Theory D clearly drove how I and various teammates ended up working.  The post really helped me understand part of why the two years I spent managing projects was so difficult.  I’m a Theory P guy at heart, and couldn’t pretend to be Theory D (much less actually believe it).

Braithwaite also writes a good follow up.

What I said about hating ObjectDataSource doesn’t count. SQLDataSource is worse. At least ObjectDataSource gives you error messages when it isn’t working. SQLDataSource appears not to work at all with stored procedures that have parameters. I found this forum thread that seemed to describe my problem. Unfortunately, none of the tactics suggested worked for me. I don’t even get error messages, just a screen with no GridView control in it. One of my colleagues looked at it and was just as stumped as I am.

Using an XSD, a couple lines of code, and an ObjectDataSource got me the result I needed with far less hassle.