Let's not override the thing that we're testing
The explanation doesn't mention that the object properties have to be mutable.
I used object.create and had the last test fail because I didn't set the attributes to be writable.
It should explicitly mention that your object should support 'foo.name = "bar";'
Still failing the last test, my own tests are asserting correctly. It would help a ton, if you could provide more details in test - like - what was expected and what was returned.
Nice kata - always train the basics)