[bug] pytest always raises a deprecation warning

[devonhk]

Description
Pytest always raises the following deprecation warning:

================================================= warnings summary ==================================================
None
  pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.

-- Docs: http://doc.pytest.org/en/latest/warnings.html

Even though I'm not using the old declaration style for fixtures.

pytest version: pytest==3.5.0
python version: 3.5.2
pip-list: https://gist.github.com/pydo/b234d9f9b9e9ca8b368dc5d86a092ac7
OS distro: Ubuntu 16.04 - 4.13.0-38-generic

Repo steps

1. Create the following test module test_file.py:

def test_foo():
    assert 1

2. Run pytest pytest test_file.py

Expected behavior
Pytest does not display any deprecation warnings in its test results

Actual behavior
This warning is always displayed:

================================================= warnings summary ==================================================
None
  pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.

-- Docs: http://doc.pytest.org/en/latest/warnings.html
======================================= 1 passed, 1 warnings in 0.01 seconds ========================================

[pytestbot]

GitMate.io thinks possibly related issues are #2469 (pytest deprecated_call contextmanager not always seeing warnings), #176 (pytest.raises(AssertionError) fails with cython modules), #767 (pytest.raises() doesn't always return Exception instance in py26), #1370 (Print out pytest-warnings?), and #3348 (pytest.raises should complain about unknown arguments).

[blueyed]

What plugins are you using? (i.e. paste the output from the whole pytest run, please).

[devonhk]

@blueyed
Plugins: cov-2.2.1
Full pytest output:

================================================ test session starts ================================================
platform linux -- Python 3.5.2, pytest-3.5.0, py-1.5.3, pluggy-0.6.0
rootdir: /home/user/Documents/Projects/sales_tool/st, inifile:
plugins: cov-2.2.1
collected 1 item                                                                                                    

src/tests/unit/test_entities_proposal_proposal_proposalItemBL.py .                                            [100%]

================================================= warnings summary ==================================================
None
  pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.

-- Docs: http://doc.pytest.org/en/latest/warnings.html
======================================= 1 passed, 1 warnings in 0.01 seconds ========================================

[blueyed]

@pydo
Please upgrade pytest-cov. It was fixed in pytest-dev/pytest-cov@065911e already.

[blueyed]

@nicoddemus
Shouldn't there be a source for the warning?
Is None supposed to be it?

[devonhk]

Thanks that fixed it.