Test Case Techniques - Error Guessing

Error Guessing:

Guessing is the art of guessing where errors can be hidden.There are no specific tools and techniques for this,but you can write test cases depending on the situation.Either when reading the functional documents or when you are testing and find an error that you have not documented.

Error guessing is based mostly upon experience,with some assistance from other techniques such as boundary value analysis.Based on experience,the test designer guesses the types of errors that could occur in a particular type of software and designs test cases to uncover them. For example,if any type of resources is allocated dynamically,a good place to look for errors is in the de-allocation of resources. Are all resources correctly de-allocated,or are some lost as the software executes?

Error guessing by an experienced engineer is probably the single most effective method of designing tests,which uncover bugs. A well-placed error guess can show a bug,which could easily be missed by many of the other test case design techniques presented in this paper.

Conversely, in the wrong hands error guessing can be a waste of time. To make the maximum use of available experience and to add some structure to this test cases design technique, it is a good idea to build a checklist of types of errors. This checklist can then be used to help "guess" where errors may occur within a unit. The checklist should be maintained with the benefit of experience gained in earlier unit tests,helping to improve the overall effectiveness of error guessing.