Install 

pip install flake8
pip install flake8-builtins
pip install pytest-flake8

Run 

pytest --flake8 .

If you'd like to run the static analysis on the directory where you have the tests files, and if you want the test-run to only include the flake8 tests then you need a way to exclude all the other tests. For this I can recommend you use a fake marker. That is, using -m qqrq you tell pytest that only run the test-functions that have a marker "qqrq". Hopefully none of your tests will use this marker and thus none of your tests will run.

Only the flake8 static code analysis. 

pytest --flake8 -m qqrq .

Configure by including the following in the setup.cfg file in the root of your project.

examples/setup-with-flake8.cfg

[tool:pytest]
flake8-ignore =
   *.py E123 E124 E126 E127 E128 E201 E202 E203 E211 E221 E222 E241 E251 E262 E265 E266 E305 E402 E501 W191 W291 W293 W391 F401 F811 F841 W605
   some_dir/*.py ALL

addopts = -p no:cacheprovider

PEP8

Flake already includes PEP8, so the following is only needed if for some reason you cannot use flake8: 

pip install pytest-pep8

examples/setup-with-pep8.cfg

[tool:pytest]
pep8maxlinelength = 2300
pep8ignore =
   *.py E123 E124 E126 E127 E128 E129 E201 E202 E203 E221 E241 E251 E262 E265 E266 E402
   some_dir/*.py ALL

addopts = -p no:cacheprovider

Cyclomtic complexity

Use-case for flake8

data = 42
other = "Data: {}".format(data)

Converted to: 

data = 42
other = "Data: {data}"

forgetting the "f" of the f-string. Now we have a variable called data that is not in use. Flake8 will report: F841 local variable 'data' is assigned to but never used