NotConstraint - samuelneff/docs GitHub Wiki
NotConstraint reverses the effect of another constraint. If the base constraint fails, NotConstraint succeeds. If the base constraint succeeds, NotConstraint fails.
```C# NotConstraint() ``` ```C# Is.Not... ```Assert.That( collection, Is.Not.Unique );
Assert.That( 2 + 2, Is.Not.EqualTo(5) );