unittest.mock.patch decorator doesn't accept args

[ashb]

Airflow uses mypy and the latest update (0.730) started causing us errors, that I think are related to invalid typing on mock.patch.

from unittest import mock

...

    @mock.patch(
        'airflow.gcp.hooks.base.GoogleCloudBaseHook.project_id',
        new_callable=PropertyMock,
        return_value=GCP_PROJECT_ID_HOOK_UNIT_TEST
    )

(from https://github.com/apache/airflow/blob/2abf0f5b70970bcd16e8cf5846ba67cf3945ecae/tests/gcp/hooks/test_cloud_build.py#L118-L122)

Causes these errors:

tests/gcp/operators/test_cloud_build.py:118: error: Argument 2 to "__call__" of "_patcher" has incompatible type "**Dict[str, Dict[str, object]]"; expected "bool"

tests/gcp/operators/test_cloud_build.py:134: error: Argument 2 to "__call__" of "_patcher" has incompatible type "**Dict[str, Dict[str, object]]"; expected "bool"

tests/gcp/operators/test_cloud_build.py:171: error: Argument 2 to "__call__" of "_patcher" has incompatible type "**Dict[str, Dict[str, object]]"; expected "bool"

(There are more examples of the same error in https://travis-ci.org/apache/airflow/jobs/590239664)

I'm not sure if this is a bug in the type definition or a bug in mypy itself.

[srittau]

I am not sure what is going on, but I can't reproduce it with this simple test case:

from unittest import mock
from unittest.mock import PropertyMock

@mock.patch(
    'airflow.gcp.hooks.base.GoogleCloudBaseHook.project_id',
    new_callable=PropertyMock,
    return_value=''
)   
@mock.patch("airflow.gcp.hooks.cloud_build.CloudBuildHook.get_conn")
@mock.patch("airflow.gcp.hooks.cloud_build.time.sleep")
def test_error_operation(self, _, get_conn_mock, mock_project_id):
    pass

[ashb]

Iiinteresting.

If I run mypy tests/gcp/operators/test_cloud_build.py it doesn't error, but it does if I run mypy tests/ -- that is probably pointing more towards a bug in mypy than a typeshed error.

[ashb]

Here's a minimal repro case at least:

import unittest
from unittest import mock

class TestCloudBuildHookWithPassedProjectId(unittest.TestCase):
    @mock.patch(
        'airflow.gcp.hooks.base.GoogleCloudBaseHook.project_id',
        new_callable=mock.PropertyMock,
        **{"return_value.classify_text.return_value": {}}
    )
    def test_error_operation(self, _, mock_project_id):
        pass

Oddly that seems to "leak" in to other files.

This style of **{} is taken from the docs btw: https://docs.python.org/3/library/unittest.mock.html#unittest.mock.Mock.configure_mock

[srittau]

Filed as python/mypy#7572, where I have a repro that doesn't use typeshed stubs. Closing here.