The term boundary case is frequently used in software engineering

Software engineering

Software Engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, and the study of these approaches; that is, the application of engineering to software...

 to refer to the behavior of a system when one of its inputs is at or just beyond its maximum or minimum limits. It is frequently used when discussing software testing

Software testing

Software testing is an investigation conducted to provide stakeholders with information about the quality of the product or service under test. Software testing can also provide an objective, independent view of the software to allow the business to appreciate and understand the risks of software...

.

For example, if an input field is meant to accept only integer values 0 - 100, entering the values -1, 0, 100, and 101 would represent the boundary cases.

It is commonly thought that three cases should be used when boundary testing (one on the boundary, and one on either side to it). However, the case on the valid side of the boundary is redundant, and so equivalence partitioning

Equivalence partitioning

Equivalence partitioning is a software testing technique that divides the input data of a software unit into partitions of data from which test cases can be derived. In principle, test cases are designed to cover each partition at least once...

 recommends skipping it..

See also

• Black box testing
  Black box testing
  Black-box testing is a method of software testing that tests the functionality of an application as opposed to its internal structures or workings . Specific knowledge of the application's code/internal structure and programming knowledge in general is not required...
  
  
• Boundary value analysis
  Boundary value analysis
  Boundary value analysis is a software testing technique in which tests are designed to include representatives of boundary values. Values on the minimum and maximum edges of an equivalence partition are tested. The values could be either input or output ranges of a software component...
  
  
• Corner case
  Corner case
  A corner case is a problem or situation that occurs only outside of normal operating parameters – specifically one that manifests itself when multiple environmental variables or conditions are simultaneously at extreme levels, even though each parameter is within the specified range for that...
  
  
• Edge case
  Edge case
  An edge case is a problem or situation that occurs only at an extreme operating parameter.For example, a stereo speaker might distort audio when played at its maximum rated volume, even in the absence of other extreme settings or conditions.An edge case can be expected or unexpected...