Don’t Let the Bad Bugs Bite!

Good Bugs Gone Bad

Software testers are in the unique position of enjoying bugs, and we actively hope to find them. There is nothing like the rush you experience when you discover a truly nasty bug. I’m talking about those wonderful Severity 1, crash-your-system, lose-your-data, smoke-coming-out-of-the-computer kind of bugs.

Those are good bugs. I love those bugs… at least I do when I find them in something I am testing. I have less love for them when they present themselves outside of work.

For example, last week, when I smelled that smokey smell that electronics make when they are burning, I did not get excited. Unsuccessful at finding the source, I wrote off the smell as a fluke. I tend to do the same thing when I am testing software and see a truly nasty bug that I can’t reproduce. That is what I consider a bad bug. I don’t love bad bugs.

Just like with software testing, writing off non-reproducible bugs as flukes can come back to bite you. Last night, the upstairs of my house was a tropical 87 degrees Fahrenheit, despite the fact that the air conditioner was running. The downstairs was only slightly cooler. I’m no Property Brother, but after some investigation I discovered that

• • the furnace’s filter was long past due for being replaced, and
  • a good portion of the air-conditioning system was frozen.

I felt certain that I had found the bug and that I had an easy fix for it. All I needed to do was change the filter and let the air-conditioner thaw, and everything would be fine, right? Wrong. Remember that burning smell that I could not track down? The friendly neighborhood HVAC repair man found out that the source of this smell was some high-voltage wiring that led to a capacitor in the blower assembly, which is what makes air-conditioning possible.

With the wires charred and the capacitor destroyed, not only would my house get even hotter, I would also be unable to travel through time. The good news was that for a sum of money that made me question my own career choice, the repairman was able to fix everything and make me cool again.

Finding Flukes

The lesson here is that whether it is a bad bug you can’t reproduce or a nasty smell you can’t track down, you need to be careful when you write something off as a fluke. Instead, look at seemingly unrelated problems you are seeing and try to imagine any possible connection. Think about all the conditions that existed when you discovered the issue—even those that should not have any connection.

For software, there are lots of ways to track down these elusive bugs. Explore the possibility that the issue is caused by a rare condition. Could the cache have something to do with it? Try testing with different users, browsers or devices. Get a second or third set of eyes to look into it.

When all is said and done, we need to be very persistent and creative when tracking down severe bugs. Even if it happens one in a thousand times, that’s one too many for the users it could impact.