Validation result

Error

Info

Checks if candidate is null.

Usage

var spec = Specification.Null<string>();

spec.IsSatisfiedBy(null); // true
spec.IsSatisfiedBy("");  // false

As property

var customerSpec = Specification.Null<Customer, string>(c => c.Comments);

customerSpec.IsSatisfiedBy(new Customer { Comments = null }); // true
customerSpec.IsSatisfiedBy(new Customer { Comments = "VIP" }); // false

Not Null

var spec = Specification.NotNull<string>();

spec.IsSatisfiedBy(null); // false
spec.IsSatisfiedBy("");  // true

As property

var customerSpec = Specification.NotNull<Customer, string>(c => c.Comments);

customerSpec.IsSatisfiedBy(new Customer { Comments = null }); // false
customerSpec.IsSatisfiedBy(new Customer { Comments = "VIP" }); // true

EF 6 support

Normally NullSpecification<T> is fully supported in EF 6. But be aware, that different types of candidates can raise exceptions.
Only entity types and primitive types are comparable.