[FIXED] What's wrong with my pytest moto context in this test?

Issue

As a frequent user of moto, I'm rather confused about the issue I'm facing. I set up a test class with a pytest fixture providing a DynamoDB table which I want to access in my test. Business as usual:

class TestDynamodbClient:

    @pytest.fixture
    def test_table(self):
        with mock_dynamodb():
            table_name = "test_table"

            dynamodb = boto3.resource('dynamodb')

            params = {
                'TableName': table_name,
                'KeySchema': [
                    {'AttributeName': 'id', 'KeyType': 'HASH'},
                ],
                'AttributeDefinitions': [
                    {'AttributeName': 'id', 'AttributeType': 'N'},
                ],
                'ProvisionedThroughput': {
                    'ReadCapacityUnits': 5,
                    'WriteCapacityUnits': 5
                }
            }

            table = dynamodb.create_table(**params)
            table.wait_until_exists()

            assert table_name in [t.name for t in dynamodb.tables.all()]  # this is to illustrate the setup works

            return table_name

Using the debugger, I confirmed the fixture to be evaluated prior to the test execution. In my test, however, the table does not exist:

    @pytest.mark.integration
    def test_recreate_table__table_exists__recreates_table(self, test_table):
        with mock_dynamodb():
            # given
            client = DynamodbClient()
    
            # this is to illustrate the setup does not work
            dynamodb = boto3.resource('dynamodb')
            assert test_table in [t.name for t in dynamodb.tables.all()]  # raises AssertionError: assert 'test_table' in []

            # when
            client.recreate_table("test_table")

            # then
            # ...

My conftest.py looks as follows:

def pytest_configure(config):
    """Mocked AWS Credentials for moto."""
    os.environ["AWS_ACCESS_KEY_ID"] = "testing"
    os.environ["AWS_SECRET_ACCESS_KEY"] = "testing"
    os.environ["AWS_SECURITY_TOKEN"] = "testing"
    os.environ["AWS_SESSION_TOKEN"] = "testing"
    os.environ["AWS_DEFAULT_REGION"] = "eu-central-1"
    os.environ["AWS_REGION"] = "eu-central-1"

    config.addinivalue_line(
        "markers",
        "integration: mark test to run only run as part of the integration test suite",
    )

I'm flabbergasted as to why the "test_table" table does not exist in my test, despite my fixture being evaluated. Does anyone have any pointers towards possible causes?

Solution

The issue was caused by the second invocation of with mock_dynamodb() in the test:

@pytest.mark.integration
def test_recreate_table__table_exists__recreates_table(self, test_table):
    with mock_dynamodb():  # this seems to create a new moto 'context'
        # given
        client = DynamodbClient()

Upon removing the invocation, everything worked as intended.

Answered By - oschlueter