Python mock.patch() not mocking imported class module

Question

I have a some code that looks like this (abridged):

## ./module_1/lambda_function.py

from shared.graphql_helpers import GraphQLClient

gql_client = GraphQLClient('http://host_url.test/')

post_event_to_consumer(event):
   response = gql_client.make_query(mutation, { 'data': event, {})

lambda_hanbdler(event, context):
   post_event_to_consumer(event['detail']

The module imported is such:

## ./shared/graphql_helpers.py

import requests

class GraphQLClient:
    def __init__(self, url):
      self.host_url = url

    def make_query(self, query, variables, headers):
        request = requests.post(self.host_url, json={'query': query, 'variables': variables}, headers=headers)
        if request.status_code != 200:
            raise Exception()
        elif request.json()['errors']:
            raise Exception()
        else:
            return request.json()['data']

The project structure is such:

module_1
    __init__.py
    lambda_function.py
    lambda_function_test.py
shared
    __init__.py
    graphql_helpers.py

My problem is that I am trying to patch GraphQLClient in lambda_function_test.py but it does not seem to be working.

My unit test looks like this:

## ./module_1/lambda_function_test.py

import os
from unittest import mock, TestCase

class TestLambdaFunction(TestCase):

    @mock.patch('module_1.lambda_function.GraphQLClient')
    def test_post_event_to_compplex(self, mock_gql_client):
        mock_gql_client = mock.Mock()
        mock_gql_client.make_query.return_value = {}

        result = post_event_to_consumer(json_data['detail'])

        assert result == None

From what I read online, patch mocks the import in the SUT's namespace, however, when I run the test, it imports the original GraphQLClient and throws a ConnectionError. I also tried removing module_1 from the path but that didn't work either.

Not sure what's incorrect here, but any help would be appreciated.