The Essential Infrastructure

Source-code control, unit testing, daily builds and bug tracking—using these support pieces daily can help you deliver robust code on a reasonable schedule.

• By Mike Gunderloy
• 02/01/2003

Sure, you know how to write perfect code but what good does that do you when you can't get it to market? In this column, I'll discuss the scaffolding that makes it possible to go from code to product, including source code control, unit testing, daily builds and bug tracking. If you're not using these support pieces in your daily work, it's likely that you could be doing a better job of delivering robust code on a reasonable schedule.

Knuckles off the Ground, Please
Brooks was writing about high-level languages and interactive programming, both radical advances at the time his book, The Mythical Man-Month: Essays on Software Engineering (Addison-Wesley), was published 21 years ago. But the sentiment applies equally well to the sorts of tools that go along with today's code production. There seems to be a sentiment among some coders that "harder is better" or, perhaps, "real coders don't need that sissy stuff." Real coders, in this view, do everything from the command line, don't need an IDE, and wouldn't be caught dead using unit tests. For all I know, they also walk around with their knuckles scraping the ground making grunting noises at one another.

If you're the sort of software developer who doesn't want to be bothered with any process at all outside of the editor, you have to ask yourself one simple question: Do you want to write code or do you want to ship code? The former is a whole lot easier than the latter, as very smart people have proved time and again. Sadly, they've mostly proved this by failing to ship products. Even Microsoft (where, whatever else you think about the company, it ships a lot of code) has had projects mire and die. Entire versions of Word and Access never made it from "neat code" to "shipping product."

Don't get me wrong. Putting the perfect process and perfect tools in place will not guarantee shipping code. (Developer and author Steve McConnell calls it "cargo cult software engineering"; see http://www.stevemcconnell.com/ieeesoftware/eic10.htm.) But not having some sort of process in place will make it much harder than it has to be to actually ship code. Fortunately, tools have progressed to the point where it's pretty easy to put together a working process for small projects.

Source Code Control
Start with source code control. To write a decent-sized application, you need to be able to experiment and change things in your code. But what do you do when your changes lead you down the rabbit hole? I've seen developers keep a separate "before" copy of their project in another directory, but really, this is exactly what source code control is good for. Put the project under source code control, check out modules to work on them, check them back in when you're done. Then if something does go wrong, just roll back to a known good version.

If you're using Visual Studio, you've already got Visual SourceSafe available. There are many other alternatives out there, too, from CVS to Perforce. Depending on your working habits and whether your team is local or distributed, you may need to evaluate a few alternatives to find one that works for you. But it's worth the effort. Once you don't feel like you're in danger of blowing up your entire project, it's a lot easier to explore when you need to solve problems.

One word of advice: Keep the time between check-ins short. Checking out your entire project and then keeping everything checked out all the time will prevent you from doing effective, granular rollbacks.

Unit Testing
Unit testing is one of the practices that very few developers I know follow. That's because most of us think that continuously testing every little thing is a waste of time. However, having recently tried using "test-first development" on a couple of projects, I have to say that it works for me. Here's the rough outline of this process:

1. When you're ready to add a new feature to your product, first write the test for the feature.
2. Verify that the test fails before you write the code.
3. Write the code.
4. Verify that the test works—and that all of your other tests still work.

Sounds crazy, doesn't it? But with the right tools, it's amazingly fast; and the productivity improvement can be dramatic. The key is to have something that makes it easy to write tests, and easy to run them. For Visual Studio .NET work, I'm using NUnit, which fits the bill for me—writing a new test is just adding a new method to a class.

Yes, you can end up with a lot of tests this way. Right now I'm working on a project with about 700 lines of code and (currently) 353 unit tests. That's 353 things that I know can go wrong, and 353 things that I know are going right. And it's amazing how much safer I feel about working on this code than I do on other projects where I don't have a good test suite.

The Build Process
You need to have a repeatable way to go from source code to shipping bits. This seems obvious—that's what Build, Rebuild Solution is for, right? Well, for all but the simplest projects, that won't do. For example, on one current project my build process has these steps:

1. Make sure everything is checked in to source code control.
2. Build the solution using the Release configuration.
3. Build the solution using the Lite configuration.
4. Build the unit test project.
5. Run NUnit to execute the unit tests.
6. Run NDoc to create developer documentation.
7. Build the setup project and put it on a share for testing.

How much work does it take to do these steps? In my case, clicking one button. That's because I've set up an automated build process. The process performs each step, saves any error messages, aborts the build if the errors are serious, and saves an XML build log for me to inspect. I'm using FinalBuilder for this job, but you could equally use makefiles or NAnt or many other systems. The key is to make sure that you automate your entire build process, with as few manual steps as possible (ideally, none). That way, everything happens on each build, and you'll never be faced with explaining "oh, I just forgot to replace the placeholder file with the real one" when you ship the wrong bits to a customer.

Bug Tracking
Finally, you need to have a bug-tracking system in place if you write code with bugs (as we all do). At a minimum, you need to keep track of what bugs are reported and whether they're fixed. Beyond that, there are many things that are nice to have: links to the source code control system, e-mail notification if you're working in a team, and more. Here I don't have a particular recommendation; I'm mostly using a home-rolled Access database for bug tracking at the moment (though I recently gave FogBugz a spin, and it looks good for distributed team development).

But whatever means you use, track those bugs! And as you fix them, write the unit tests that would have caught them in the first place. We all have bugs in our code; that's normal. But you should never have the same bug show up again after it's been fixed.

Continuous Integration?
So that's my four-part program for getting your code out the door: control the source, control the tests, control the build, control the bugs. Any reasonably disciplined developer should be able to manage this. Where it gets interesting is when you carry these processes to extremes. As you might expect, extreme programming (XP) does just that, with a notion called "continuous integration."

What continuous integrations does is combine the check-in, build and test processes into one big process. An automated process monitors the source code control repository, and when it spots a changed file, it kicks off the build process and then the test process. You can read a good explanation of how this works in practice on Martin Fowler's Web site at http://www.martinfowler.com/articles/continuousIntegration.html. I haven't yet tried this on any project, but it's certainly worth thinking about. By reducing the manual steps even more, continuous integration should contribute to the goal of having working executables built from the latest source code at all times. When I try it, I'll report back.