It starts with a situation, and with some wiggle room.
"We're having this issue.... sometimes."
"We're having a problem... with some users."
"Clients are sending us screenshots that look like this but we can't make that problem happen."
The hunt is on. Assemble the data hounds!
Let's work through what we know:
- we have gotten more complaints for it on new users
- it hasn't occurred in our dev configuration, but it has in the client's test configuration
- we've gotten reports of the problem on at least Firefox and IE 7
- when it happens, it's always CSS styles that look funny or wrong
Now we can start to eliminate possibilities:
From there, we know to hit the test server on Firefox with a new user. I did that, and reproduced the problem.
NOW we're getting somewhere.
With a little help from Firebug, it became obvious quickly that the problem was that any user who was seeing the EULA (new users only) had some of the styles redefined outside the CSS in the EULA itself. A little more digging turned up the fact that whoever had created the EULA for the client's test system had done so by saving a Microsoft Word document as an html page with inline styles. Some of the style names overlapped, and there's our bug!
Often, I get my prey and another bug is understood. Sometimes, the hounds and I go home defeated.
Either way, embrace the thrill of the bug hunt. It's only part of what we do, but boy does it feel good to catch a devious defect.