KeyError: 'PYTEST_CURRENT_TEST' when running in pytest

[acmiyaguchi]

The latest version of moto (1.3.14) is breaking in the following test scenario:

test.py

import pytest
from moto import mock_s3
import boto3

@pytest.fixture()
def client():
    mock_s3().start()
    client = boto3.resource("s3")
    client.create_bucket(Bucket="test-bucket")
    yield client
    mock_s3().stop()


def test_moto_fixture(client):
    return True

tox.ini

[tox]
envlist = py27
skipsdist = True

[testenv]
deps=
    pytest
    boto3
    moto == 1.3.14
commands=
    python -m pytest test.py {posargs}

Running tox with these two files at the root returns the following error.

self = {}, key = 'PYTEST_CURRENT_TEST', args = ()

    def pop(self, key, *args):
        unsetenv(key)
>       return self.data.pop(key, *args)
E       KeyError: 'PYTEST_CURRENT_TEST'

.tox/py27/lib/python2.7/os.py:505: KeyError

Setting moto == 1.3.13 fixes this.

[bblommers]

Running this with Python37 gives a bit more background information:

>       mock_s3().stop()

test.py:11: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
.tox/py37/lib/python3.7/site-packages/moto/core/models.py:75: in stop
    self.env_variables_mocks.stop()
.tox/py37/lib/python3.7/site-packages/mock/mock.py:1813: in __exit__
    self._unpatch_dict()
.tox/py37/lib/python3.7/site-packages/mock/mock.py:1805: in _unpatch_dict
    in_dict.update(original)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

args = [None], kwds = {}, self = environ({}), other = None

    def update(*args, **kwds):
        ''' D.update([E, ]**F) -> None.  Update D from mapping/iterable E and F.
            If E present and has a .keys() method, does:     for k in E: D[k] = E[k]
            If E present and lacks .keys() method, does:     for (k, v) in E: D[k] = v
            In either case, this is followed by: for k, v in F.items(): D[k] = v
        '''
       ...
E               TypeError: 'NoneType' object is not iterable

.tox/py37/lib/python3.7/_collections_abc.py:846: TypeError

The erring line was introduced in this PR: #2285

[bblommers]

In your test, you're introducing two instances of the class 'mock_s3'. The PR above introduced class-level variables to mock AWS credentials, so it's now required to call 'start()' before calling 'stop()' on the same class-instance.

Changing your test case to either one of the following setups will work:

import pytest
from moto import mock_s3
import boto3


@pytest.fixture()
@mock_s3()
def client():
    client = boto3.resource("s3")
    client.create_bucket(Bucket="test-bucket")
    yield client


def test_moto_fixture(client):
    return True

Or

import pytest
from moto import mock_s3
import boto3


@pytest.fixture()
def client():
    mock = mock_s3()
    mock.start()
    client = boto3.resource("s3")
    client.create_bucket(Bucket="test-bucket")
    yield client
    mock.stop()


def test_moto_fixture(client):
    return True

[acmiyaguchi]

Thanks for the tip, using the same mocking instance fixes the problem that I was seeing. The first setup doesn't propagate the mock_s3 environment into the cases where the fixture is used, though.

[acmiyaguchi]

For reference, this is how I generated my testing fixtures: #620 (comment)