The testCase model element can be used in SystvIL but it only applies to software

Validation of a requirement can be indicated using a satisfiedBy relationship to a testCase

Only the verdict model element (which can be a property of a testCase) can have a verifies relationship to a requirement.

A requirement can have a vehfiedBy relationship to a testCase even if the test has not yet been conducted or even fully specified

testCase is part of the UML Testing Profile and cannot be used with SysML.