I’m seeing this same issue, had figured out what’s happening. It’s not caused by library versions, I just updated to use latest version for the libraries

• boto: 2.49.0
• boto3: 1.9.232
• botocore: 1.12.232
• moto: 1.3.13

moto is injecting the botocore_stubber to botocore.handlers.BUILTIN_HANDLERS, but for my case, there’s another import from code which includes a line of s3 = boto3.client('s3') call outside of functions, That import is before the import moto in my test, so it’s causing boto creating the DEFAULT_SESSION without the extra botocore_stubber handler, and it was used when the AWS call in test supposed to be mocked.

The workaround is to set boto3.DEFAULT_SESSION to None before the usage of moto mock, and this will cause a creation of new DEFAULT_SESSION with the botocore_stubber handler.

I did it with a pytest fixture

@pytest.fixture(scope="session")
def clear_default_boto3_session(): 
    boto3.DEFAULT_SESSION = None

def test_with_moto(clear_default_boto3_session):
    with mock_s3():
        s3 = boto3.resource('s3', region_name='us-east-1')
        assert [b for b in s3.buckets.all()] == []

Update: I also have to move the line of boto3.client in my code into a method to get the mock work with my code.

Update again: Instead of resetting the boto3.DEFAULT_SESSION and move my boto3.client call in code, I added import boto3 into my tests/__init__.py so it gets imported before anything else.

Maintainer time is premium in open-source. If you need it merged, hop on the community and become maintainer. Otherwise, fork and host on a private PyPI.

On Mon, Oct 11, 2021, 03:02 Cyril Scetbon @.***> wrote:

It seems there’s been a PR opened for 3 months, any reason why it’s taking so long to get it reviewed, merged in etc… ?

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+1 Just hit this today.

hello, I still have the same issue with moto==2.1.0 boto==2.49.0 boto3==1.17.84 botocore==1.20.112. I tried the different solution shared in this issue without any success. Any idea how to solve this?

@spulec here’s a simplified example of the issue I’m seeing https://gist.github.com/xiang-zhu/d441289bc2715b3e6d8723d7d3cd31af

This test will fail with InvalidAccessKeyId error as botocore api call was not mocked properly.

If you move the from moto import mock_s3 line in test_example.py before the from example import list_buckets the mock will be properly applied.

The issue become harder to notice when you have multiple tests file, and import from code happening in other tests.

Search through README, turns out this is a known issue https://github.com/spulec/moto#what-about-those-pesky-imports

@bblommers, in case you might be interested the problem seems to persist:

module 1

def get_s3_client(aws_session, aws_region_name, debug):
    """ :return: Returns an S3 boto3 Client object """
    config = Config(retries={'max_attempts': 3, 'mode': "adaptive"})
    client = aws_session.client("s3", region_name=aws_region_name, config=config)

    if debug:
        patch_client(client)

    return client

module 2

s3_client_mock = get_s3_client(
    boto3.Session(),
    aws_region_name=AWS_REGION_NAME,
    debug=True
)

# This method fails because it is using the AWS credentials
result = s3_client_mock.list_buckets()

requirements

boto3==1.23.6
moto[s3]==4.0.10

It doesn’t work better for me with this new release.