Should referential integrity from the database be unit tested?

Question

Lets assume I have a Customer and Order table.

When I do a Customer_Delete_Test do you also Assert if the related Orders are deleted too or

do you rely on the referential integrity between the tables like On Cascade Delete ?

Answer 1

I would unit test to ensure that you have constructed your database correctly and is behaving as you are expecting it to behave.

The database vendors may have done their job but that is only part of the story. Have you done yours correctly?