Thursday, July 30, 2009

A Different Test

Sometimes the test you do.... is not the test you intended to do.

Case in point:
Today I went to do a simple upgrade test. On a given platform in a given configuration, upgrade from the most recent released version to the new version that's coming out. Simple.

I completely forgot that we'd tested a "power event" on that system earlier this morning. (Note: for "power event" read "a tester went in and pulled the plug on the power strip for that entire system"). The system handled the "power event" just fine, but I hadn't yet gone in and completed the products startup validation process.

So my system was not in a good state when it started the upgrade. And the upgrade failed exactly like it was supposed to.

Not exactly the test I intended to do, but it was a perfectly valid test. So what's the moral of the story?

If you're attempting at test, and it does something unexpected, take a quick look. You may have done a different test.

Now off to do the test I meant to do originally!

2 comments:

  1. I can't tell you how many times I've found bugs that way. I sometimes wish there was an equivalent of a fuzzing tool for machine states. Oh, wait, there's Holodeck, I just can't afford it...

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  2. There are also various tricks we can use to fuzz things in homegrown test utilities. They're not necessarily the fanciest things in the world, but you can do a lot of basic tests with a random generator and a list of plausible values.

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