Constraints should be used as NUnit Assert.That, for example:
Constraints
.Check(() => arg1, Is.Not.Null.And.Not.Blank) // arg1 is not null and not blank
.Check(() => arg2, Is.Not.Empty) // arg2 is not empty
.Check(() => arg3, Is.InRange(1,10).Or.InRange(-10, -1)); // arg3 is between 1 and 10 or -10 and -1
Constraints should be used as NUnit Assert.That, for example: