Sorry but this is a garbage take. Typing negates the need for writing useless tests that just verify the correct value types are passed - it does not negate the need for writing functional tests.
Where did you come up with this?
You seem to not understand duck typing.
Functional tests will test the correct types, too.
Edit: If you need an object that swims and quacks, you don't need to care if it is a rubber duck or an animal.
And static types are for people who are too lazy to write test code.