The Parse Null operator uses the keyword 'null' to indicate a null value.

when input is⇓ story test fixture check plain test 'sample domain' set name null check name null check namelength exception[NullReferenceException] check name Bob set name Bob check name null sample domain set name null check name null check namelength exception[NullReferenceException] check name Bob expected null actual set name Bob check name null expected Bob actual

'sample domain' set name null check name null check namelength exception[NullReferenceException] check name Bob set name Bob check name null

then output is

sample domain set name null check name null check namelength exception[NullReferenceException] check name Bob expected null actual set name Bob check name null expected Bob actual