corner case

corner case (plural corner cases)

1. (chiefly engineering) A problem or situation that occurs only when two or more operating parameters are at extreme values, or when two or more unusual operating circumstances happen to coincide.

   Hypernym: edge case

   • 2001, Faisal I. Haque, Khizar A. Khan, Jonathan Erik Michelson, The Art of Verification with Vera, Verification Central LLC

     The smallest and largest legal packet sizes are examples of the first type of corner case. This type of boundary condition is usually specified by or easily inferred from the externally published feature set of the design.

   • 2006, Harry D. Foster, Adam C. Krolnik, David J. Lacey, Assertion-Based Design, Springer Science & Business Media, →ISBN, page 58:

     Using assumptions, however, our goal is to prove correctness while finding complex corner-case bugs.

2. (by extension) Any unusual scenario.
   • 2013, Adam Boduch, jQuery UI Cookbook, Packt Publishing Ltd, →ISBN:

     However, there is a corner case during which we don't want to trigger this event, and that is when the widget is being instantiated for the first time.

   • 2015, Patroklos Papapetrou, Jonathan LALOU, Android Application Development with Maven, Packt Publishing Ltd, →ISBN, page 76:

     Furthermore, Robolectric doesn't test activities against real devices or emulators and this might not catch corner case or incompatibilities or issues with particular versions and devices.