olemus
Wiktionary:
1 a problem or situation that occurs only at an extreme (maximum or minimum) operating parameter or under other unusual operating conditions

ülevaateid
https://en.wikipedia.org/wiki/Edge_case

https://chisellabs.com/glossary/what-is-an-edge-case/

https://blog.logrocket.com/product-management/edge-case-software-development/

https://testsigma.com/blog/edge-case-testing/