Anomaly in software

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In software testing an anomaly is everything that differs from expectation.^[1] This expectation can result from many things like from a document (e.g. the expected behaviour is not always written down explicitly, so the developer may implement it differently) or from a person's view (e.g. the person has different opinion regarding usability) or experiences (e.g. the specification is not clear on one thing and the person also knows competitor products, where such a feature is implemented or where the tested software behaves different than these).

1 Examples for anomalies
2 See also
3 References
4 External links

An anomaly also can point to a new feature or an usability problem, because the software may be correct with respect to the specification, but has room for improvement.

Another possibility for an anomaly is that a tester executed the testcase incorrectly and therefore the expected result is also incorrect (Garbage In, Garbage Out). Some other common terms for software anomalies are: bug, fault, failure, error, defect, problem, deviation, glitch, incident, crash. According to IEEE, the word anomaly should be favoured because it has a more neutral meaning.

'Software' in this article is more than just source code.^[2] It also refers to: programs, procedures and documentation, and data for the concerning processing on a computer system. Testing software ("testware") is also regarded as software in this context.

The time and place of anomalies can be pretty anywhere in the (Software development life cycle) - it should not be seen from end user perspective only. Most people see anomalies (e.g. failures) during analytical quality assurance measures, but in fact the reason for this anomaly probably ocurred earlier. This is why preventive quality assurance are more important: anomalies are found earlier, which can result in lower costs.

[edit] Examples for anomalies

Famous anomalies
different screens of death: Screen of Death, Blue Screen of Death
an anomaly in the game Super Mario Bros.: the Minus World
On 8th December 2005 hundreds of thousands of people wanted to buy at the stock exchange Tokio shares which were offered for 1 Yen. What did happen? There were two input-fields: price and amount of shares to sell. One person wanted to sell only one share for 610000 Yen (around 4300 Euro), but he confused and typed: 610000 shares for 1 Yen.
in white box testing: data flow anomaly^[3] and control flow anomaly
Easter egg
buffer overflow, deadlock, division by zero, memory leak, hang
more examples you can find in following categories: Category:Computer errors, Category:Programming bugs, Category:Screens of death