Resource exhaustion and other uncommon testing scenarios

The idea of this post and part of the contents are from the fantastic book The Pragmatic Pogrammer.

We don't usually test for most of the following resources:

  • Anti-virus software: Some of them have aggressive heuristics that can confuse a binary socket communication with a trojan.
  • Color depth: How does your website looks in 256 colors? and on a mobile device (if supported)?
  • CPU bandwith: Slowness, long response wait times, too CPU intensive calculations.
  • Disk bandwith: Similar to CPU bandwith, but caused ony when performing I/O.
  • Disk space: Getting out of available disk space (or quota space) while writing any file.
  • Fonts and DPI: Does your application support custom DPI schemes (for example, bigger characters)? Have you tried launching your application on a windows without your used font?
  • Memory: OutOfMemory exceptions in .NET, Garbage collector being very slow or being called too much...
  • Network bandwith: Timeouts in web services, slowness when having big network I/O...
  • Power shortages: unplug the AC adaptor of your desktop pc while testing the application, and then launch it again. Does it wor, or at least recovers from the sudden shutdown?
  • Restrictive ACLs and Account Policies: Don't assume your application will be able to write into windows registry, test for it (at least when launching the application if you're mad with performance hits).
  • Video/Screen resolution: Have you tried your WinForms application in a 640x480 resolution? and in one of the now widely spread netbooks (which usually have wanky resolutions like 1024x600)?
  • Wall clock time: Human perception of passing of time, versus time taken by a computer to complete a task. Do not take tests as "the whole truth", human testing of applications is always needed.

An example of the wall clock time is pre-Service Pack 1 Vista's file copy, which was in theory faster and better but actually took longer to copy the same file than in XP for a normal user (more info about it can be found here).

Posted by Kartones on 2009-08-04

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