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Wednesday, July 9, 2008

Ten software testing traps

Ten software testing traps
By Michelle Davidson
Everyone at some point in their careers faces difficulties. The problem could be not having enough resources or time to complete projects. It could be working with people who don't think your job is important. It could be lack of consideration and respect from managers and those who report to you.
Software testers aren't exempt from this. But as Jon Bach pointed out in his session titled "Top 10 tendencies that trap testers" that he presented at StarEast a couple weeks ago, software testers often do things that affect their work and how co-workers think about them.
Bach, manager for corporate intellect and technical solutions at Quardev Inc., reviewed 10 tendencies he's observed in software testers that often trap them and limit how well they do their job.
"If you want to avoid traps because you want to earn credibility, want others to be confident in you, and want respect, then you need to be cautious, be curious and think critically," he said.
Here's a look at what Bach considers the top 10 traps and how to remedy them:
10. Stakeholder trust: This is the tendency to search for or interpret information in a way that confirms your preconceptions. But what if a person's preconceptions are wrong? You can't automatically believe or trust people when they say, "Don't worry about it," "It's fixed," or "I'll take care of it."
Remedies include learning to trust but then verify that what the person says is correct. Testers should also think about the tradeoffs compared with opportunity costs, as well as consider what else might be broken.
9. Compartmental thinking: This means thinking only about what's in front of you. Remedies include thinking about opposite dimensions -- light vs. dark, small vs. big, fast vs. slow, etc. Testers can also exercise a brainstorm tactic called "brute cause analysis" in which one person thinks of an error and then another person thinks of a function.
8. Definition faith: Testers can't assume they know what is being asked of them. For example, if someone says, "Test this," what do you need to test for? The same goes for the term "state." There are many options.
What testers need to do is push back a little and make sure they understand what is expected of them. Is there another interpretation? What is their mission? What is the test meant to find?
7. In-attentional blindness: This is the inability to perceive features in a visual scene when the observer is not attending to them. An example of this is focusing on one thing or being distracted by something while other things go on around you, such as a magic trick.
To remedy this, testers need to increase their situational awareness. Manage the scope and depth of their attention. Look for different things and look at different things in different ways.
6. Dismissed confusion: If a tester is confused by what he's seeing, he may think, "It's probably working; it's just something I'm doing wrong." He needs to instead have confidence in his confusion. Fresh eyes find bugs, and a tester's confusion is more than likely picking up on something that's wrong.
5. Performance paralysis: This happens when testers are overwhelmed by the number of choices to begin testing. To help get over this, testers can look at the bug database, talk with other testers (paired testing), talk with programmers, look at the design documents, search the Web and review user documentation.
Bach also suggests trying a PIQ (Plunge In/Quit) cycle -- plunge in and just do anything. If it's too hard, then stop and go back to it. Do this several times -- plunge in, quit; plunge in, quit; plunge in, quit. Testers can also try using a test planning checklist and a test plan evaluation.
4. Function fanaticism: Don't get wrapped up in functional testing. Yes, those types of tests are important, but don't forget about structure tests, data tests, platform tests, operations tests and time tests. To get out of that trap, use or invest in your own heuristics.
3. Yourself, untested: Testers tend not to scrutinize their own work. They can become complacent about their testing knowledge, they stop learning more about testing, they have malformed tests and misleading bug titles. Testers need to take a step back and test their testing.
2. Bad oracles: An oracle is a principle or mechanism used to recognize a problem. You could be following a bad one. For example, how do you know a bug is a bug? Testers should file issues as well as bugs, and they should mention in passing to people involved that things might be bugs.
1. Premature celebration: You may think you've found the culprit -- the show-stopping bug. However, another bug may be one step away. To avoid this, testers should "jump to conjecture, not conclusions." They should find the fault, not just the failure.
Testers can also follow the "rumble strip" heuristic. The rumble strip runs along most highways. It's a warning that your car is heading into danger if it continues on its current path. Bach says, "The rumble strip heuristic in testing says that when you're testing and you see the product do strange things (especially when it wasn't doing those strange things just before) that could indicate a big disaster is about to happen."

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