I'm trying to run some tests on a custom apache airflow hook created. The tests pass but there is this weird error(which does not affect the tests) as in below. It is weird because BrazeHook can be imported and be used and does not cause error in any other class or tests

[2019-06-21 16:11:27,748] {{settings.py:182}} INFO - settings.configure_orm(): Using pool settings. pool_size=5, pool_recycle=1800, pid=53175
[2019-06-21 16:11:29,243] {{plugins_manager.py:143}} ERROR - cannot import name 'BrazeHook'
Traceback (most recent call last):
  File "/xxxxx/xxx/venv/lib/python3.6/site-packages/airflow/plugins_manager.py", line 137, in <module>
    m = imp.load_source(namespace, filepath)
  File "/xxxxx/bloodflow/venv/lib/python3.6/imp.py", line 172, in load_source
    module = _load(spec)
  File "<frozen importlib._bootstrap>", line 684, in _load
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/xxxx/xxx/plugins/operators/s3_to_braze_operator.py", line 9, in <module>
    from plugins.hooks.braze_hook import BrazeHook
ImportError: cannot import name 'BrazeHook'
[2019-06-21 16:11:29,246] {{plugins_manager.py:144}} ERROR - Failed to import plugin /xxxx/xxx/plugins/operators/x_to_braze_operator.py

Ran 1 test in 0.071s

OK

Class

import requests

from braze.client import BrazeClient, BrazeClientError, BrazeInternalServerError


class BrazeImportError(Exception):
    def __init__(self, message):
        """
        Error occured while trying to import the users data into Braze

        :param str message: error message returned by Braze or message out ot anu other exception.
        """
        self.message = message
        super(BrazeImportError, self).__init__()


class BrazeHook(BaseHook):

    def __init__(self, braze_conn_id='braze', *args, **kwargs):
        self.connection = self.get_connection(braze_conn_id)

    def track(self, attributes=None, events=None, purchases=None):
        """
        adds/modifies user data through /users/track endpoint of braze
        :param attributes: dict or list of user attributes dict (external_id, ... }
        :return:
        :throws BrazeClientError encapsulation various errors returned by Braze
        """
        try:
            client = BrazeClient(api_url=self.connection.host, api_key=self.connection.extra_dejson.get('api_key'))
            return client.user_track(attributes=attributes, events=events, purchases=purchases)
        except requests.exceptions.ConnectionError as ce:
            raise BrazeImportError(ce.args[0])
        except (BrazeClientError, BrazeInternalServerError) as be:
            raise BrazeImportError(message=str(be))

Test

class TestBrazeHook(unittest.TestCase):

    @responses.activate
    def test_request_path(self):
        responses.add(responses.POST, "https://brazeurl/users/track",
                      json={'errors': u'', u'message': u'success', 'status_code': 200, 'success': True}, status=201)

        handler = BrazeHook(braze_conn_id="braze")

        response = handler.track(attributes=[])

        self.assertEqual(201, response['status_code'])

UPDATE adding the operator that the error message refers to, as requested in the comments

class S3ToBrazeOperator(BaseOperator):
    """
    Copies Reader Score based audiences from S3 to Braze
    """

    template_fields = ()
    template_ext = ()
    ui_color = '#ededed'

    @apply_defaults
    def __init__(self,
                 s3_bucket,
                 s3_path,
                 s3_conn_id,
                 braze_conn_id,
                 columns,
                 *args, **kwargs):
        super(S3ToBrazeOperator, self).__init__(*args, **kwargs)
        self.s3_bucket = s3_bucket
        self.s3_path = s3_path
        self.s3_conn_id = s3_conn_id
        self.braze_conn_id = braze_conn_id
        self.columns = columns

    def execute(self, context):
        request_handler = BrazeHook(braze_conn_id=self.braze_conn_id)

        ....

        scores = dd.read_csv(f"s3://{self.s3_bucket}/{self.s3_path}/*",
                             sep=";", compression="gzip", header=None, storage_options=options).compute()

        scores.columns = self.columns

        attributes = []
        # batches the results according to step size
        for batch in chunk(scores, BRAZE_API_STEP):

            batch.apply(lambda user: {
                "external_id": user.user_id,
                ....
            }, axis=1).apply(lambda attribute: attributes.append(attribute))

            try:
                request_handler.track(attributes=attributes)
            except Exception as e:
                logging.error("Error {}".format(str(e)))
                raise