Mocking SQLAlchemy test within Strawberry/FastAPI - fastapi

Question

I'm working on creating unit tests for a FastAPI, Strawberry, and SQLAlchemy setup. The current API is working and returning data correctly, but I cannot figure out how to mock the underlying database for unit tests. Would love any help/guidance to figure out this issue.
Below is the test code I"m currently working with, which I'm hoping will be enough to solve this issues but happy to post more if it helps. Running this currently will produce and output of ExecutionResult(data=None, errors=[GraphQLError("'NoneType' object is not subscriptable", locations=[SourceLocation(line=3, column=13)], path=['biomarkers'])], extensions={}), which seems to indicate that it is almost working but not quite reaching the mocked data within UnifiedAlchemyMagicMock.
import uuid
import unittest
from unittest import mock
import strawberry
from strawberry.extensions import Extension
from alchemy_mock.mocking import UnifiedAlchemyMagicMock
from app.api.api_v1 import api
from app.models import biomarker as biomarker_models
class MockSession:
'''Create Mock Session for Db'''
session = UnifiedAlchemyMagicMock(data=[
(
[mock.call.query(biomarker_models.Biomarker)],
[biomarker_models.Biomarker(
name="hello",
id=uuid.UUID('1a8d8791-946c-4fc4-8f5d-1b0c4f5ee2f5'),
quest_biomarker_code="quest"),
biomarker_models.Biomarker(
name="test",
id=uuid.uuid4(),
quest_biomarker_code="palazo")]
)
])
class MockRequest(Extension):
'''Mock Request state for context'''
def on_request_start(self):
self.execution_context.context["db"] = MockSession()
def on_request_end(self):
self.execution_context.context["db"].close()
class BioMarkerTestCase(unittest.TestCase):
'''Test Biomarker'''
def setUp(self) -> None:
self.strawberry_schema = strawberry.Schema(
query=api.Query,
mutation=api.Mutation,
extensions=[MockRequest],
types=api.QUERY_TYPE_LIST)
def test_query_get_all(self) -> None:
'''test biomarker query'''
query = """
query {
biomarkers {
id
name
whyItMatters
questBiomarkerCode
modeOfAcquisition
questRefRangeLow
questRefRangeHigh
optimalRangeLow
optimalRangeHigh
withinRangeRecommendations
belowRangeRecommendations
aboveRangeRecommendations
crossReferenceBiomarkers
notes
resourcesCited
measurementUnits
isCritical
resultDataType
critical{
id
biomarkerId
isPriority1
priority1Range
isPriority2
priority2Range
}
}
}
"""
query_result = query_result = self.strawberry_schema.execute_sync(query)
self.assertIsNotNone(query_result.data)

Answer 1

When using
query_result = query_result = self.strawberry_schema.execute_sync(query)
the context_value is defaulted to None, which I think is the cause of your errors.
try with:
query_result = query_result = self.strawberry_schema.execute_sync(query, context_value={})