Editing Assertion (software development) (section)

{{short description|In computer programming, statement that a predicate is always true at that point in code execution}}
{{About|the computer programming concept|assertions in the context of the [[Security Assertion Markup Language]] (SAML) open standard|Security Assertion Markup Language#Assertions}}

In [[computer programming]], specifically when using the [[imperative programming]] paradigm, an '''assertion''' is a [[Predicate (mathematical logic)|predicate]] (a [[Boolean-valued function]] over the [[state space]], usually expressed as a [[logical proposition]] using the [[variable (programming)|variable]]s of a program) connected to a point in the program, that always should evaluate to true at that point in code execution. Assertions can help a programmer read the code, help a [[compiler]] compile it, or help the program detect its own defects.

For the latter, some programs check assertions by actually evaluating the predicate as they run. Then, if it is not in fact true – an assertion failure – the program considers itself to be broken and typically deliberately [[Crash (computing)|crashes]] or throws an assertion failure [[exception handling|exception]].