The Benefits of Testing Legacy Code

Sure. We all love to test against the latest and greatest, shiny new web applications. But what happens if you need to test older legacy code?

Could there actually be a benefit to being involved in testing older code? You might be surprised by the answer. Not only can working on older code give you added job security, but it also might expand your skills – enabling you to tackle any testing effort, new or old.

Today we’ll be talking with the man sometimes referred to as “the code whisperer.” This Bob Vila of code talks with us about testing legacy applications.

About Scott Ford

Scott Ford is the Founder and Chief Code Whisperer at Corgibytes, a software consultancy whose mission is to maintain and improve the world’s existing codebases. Scott specializes and thrives on breathing new life into existing projects.

Quotes & Insights from this Test Talk

• Use modern test tools when testing legacy code
• Fear shouldn’t get it the way of us making our application’s code base better.
• Want a recession proof careers? Legacy code might be for you.
• It’s tempting to think that we can minimize software problems by avoiding them, but, unfortunately, it always catches up with us.
• Corgibytes has a bunch of services to help you with your legacy code
• Mocking Libraries can is usually a quick win to help you with testing legacy code
• So how do we start making changes in a legacy project? The first thing to notice is that, given a choice, it is always safer to have tests around the changes that we make.  When we change code, we can introduce errors; But when we cover our code with tests before we change it, we’re more likely to catch any mistakes that we make.

Michael Feathers: The Legacy Code Change Algorithm

When you have to make a change in a legacy code base, here is an algorithm you can use.

1. Identify change points.
2. Find test points.
3. Break dependencies.
4. Write tests.
5. Make changes and refactor.

Resources

• Working Effectively with Legacy Code – Michael Feathers
• .Net Rocks podcast episode 1062 Taking Over a Brownfield Application with Scott Ford

Connect with Scott

• Twitter: @mscottford
• Blog: http://mscottford.com/
• Company: Corgibytes

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