There are a few additional tests that are being implemented in Python here.

They include:

1. Test that collection options are forwarded correctly.
2. Test that the returned encryptedFields is in fact a copy of the values in AutoEncryptionOpts.encryptedFieldsMap, and not a reference to the same value (in languages that allow this). 
3. Test encryptedFields that have mixed Null and normal keys.
4. Test that the exception raised when creating a data key fails contains the partial encryptedFields.