what is a bug?

 a software bug occurs when one or more of the following five rules is true: 
T'T8^nc4]}[0  1) The software doesn't do something that product specification says it should do.51Testing软件测试网n!Q;S,~V*b5u?R
  2) The software does somethinng that product specification says it shouldn't do
&q,xCp#v\y-zG0  3) The software does somerhing that product specification doesn't mention(提及)51Testing软件测试网j!f vK L/l8^L
  4) The software doesn't do something that product specification doesn't mention but should do.
\d \z I^3gi0  5) The sofrware is difficult to understand,hard to use,slow or --in the software tester's eyes -- will51Testing软件测试网6[{+@1xl3a_`b
be viewed by the end user as just plain not right.51Testing软件测试网0\v9tp0`NSm X
                                                --摘自《Software Testing》
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