[Question] Is the cfn package compatible with `cfn test` ?

I've written a custom resource using the cfn package. We want to publicly publish the custom resource but cannot get the `cfn test` contract test suite to run (I do have a rpdk json file). The best I can tell our code is not called at all.

Every test fails with
```
../../.virtenv/aws-cfn-cli/lib/python3.8/site-packages/rpdk/core/contract/suite/resource/handler_create.py:31: in created_resource
_status, response, _error = resource_client.call_and_assert(
../../.virtenv/aws-cfn-cli/lib/python3.8/site-packages/rpdk/core/contract/resource_client.py:668: in call_and_assert
status, response = self.call(action, current_model, previous_model, **kwargs)
../../.virtenv/aws-cfn-cli/lib/python3.8/site-packages/rpdk/core/contract/resource_client.py:689: in call
status = OperationStatus[response["status"]]
E KeyError: 'status'
```

Lambda's output is always
```
START RequestId: 45e19f24-1001-4be9-ad69-2fa39b3592bd Version: $LATEST
2022/06/28 19:17:18 sending status failed: unknown event request type:
Put "": unsupported protocol scheme "": Error
null
END RequestId: 45e19f24-1001-4be9-ad69-2fa39b3592bd
```
None of my logging shows-up in the lambda's output.

Do I need to fallback to cloudformation-cli-go-plugin?