Assert

Assert[test] represents the assertion that test is True. If assertions are enabled and test is not True, an assertion failure is generated.

Examples

Basic assertion:

Assert[1 + 1 == 2]
(* Null - passes silently *)

Failing assertion:

Assert[1 + 1 == 3]
(* Assertion failure message if assertions enabled *)

With tag:

Assert[x > 0, "PositiveCheck"]

Please visit the official Wolfram Language Reference for more details.