How to get PyTest fixtures to autocomplete in PyCharm (type hinting)

Question

I had a bear of a time figuring this out, and it was really bugging me, so I thought I'd post this here in case anyone hit the same problem...

(and the answer is so dang simple it hurts :-)

The Problem

The core of the issue is that sometimes, not always, when dealing with fixtures in PyTest that return objects, when you use those fixtures in a test in PyCharm, you don't get autocomplete hints. If you have objects with large numbers of methods you want to reference while writing a test, this can add a lot of overhead and inconvenience to the test writing process.

Here's a simple example to illustrate the issue:

Let's say I've got a class "event_manager" that lives in:

location.game.events

Let's further say that in my conftest.py file (PyTest standard thing for the unfamiliar), I've got a fixture that returns an instance of that class:

from location.game.events import event_manager

...

@pytest.fixture(scope="module")
def event_mgr():
    """Creates a new instance of event generate for use in tests"""
    return event_manager()

I've had issues sometimes, (but not always - I can't quite figure out why) with classes like this where autocomplete will not work properly in the test code where I use the fixture, e.g.

def test_tc10657(self, evt_mgr):
    """Generates a Regmod and expects filemod to be searchable on server"""
    evt_mgr.(This does not offer autocomplete hints when you type ".")

So the answer is actually quite simple, once you review type hinting in PyCharm: http://www.jetbrains.com/help/pycharm/2016.1/type-hinting-in-pycharm.html

Here's how to fix the above test code so that autocomplete works properly:

from location.game.events import event_manager 

...

def test_tc10657(self, evt_mgr: event_manager):
    """Generates a Regmod and expects filemod to be searchable on server"""
    evt_mgr.(This DOES offer hints when you type "." Yay!)

Notice how I explicitly type the fixture as an input parameter of type event_manager.

Answer 1

Also if you add a docstring to a function and specify the type of the the parameters, you will get the code completion for those parameters.

For example using pytest and Selenium:

# The remote webdriver seems to be the base class for the other webdrivers
from selenium.webdriver.remote.webdriver import WebDriver

def test_url(url, browser_driver):
    """
    This method is used to see if IBM is in the URL title
    :param  WebDriver browser_driver: The browser's driver
    :param str url: the URL to test
    """
    browser_driver.get(url)
    assert "IBM" in browser_driver.title

Here's my conftest.py file as well

import pytest
from selenium import webdriver

# Method to handle the command line arguments for pytest
def pytest_addoption(parser):
    parser.addoption("--driver", action="store", default="chrome", help="Type in browser type")
    parser.addoption("--url", action="store", default='https://www.ibm.com', help="url")


@pytest.fixture(scope='module', autouse=True)
def browser_driver(request):
    browser = request.config.getoption("--driver").lower()
    # yield the driver to the specified browser
    if browser == "chrome":
        driver = webdriver.Chrome(executable_path='/path/to/chromedriver')
    else:
        raise Exception("No driver for browser " + browser)
    yield driver
    driver.quit()


@pytest.fixture(scope="module")
def url(request):
    return request.config.getoption("--url")

Tested using Python 2.7 and PyCharm 2017.1. The docstring format is reStructuredText and the "Analyze Python code in docstrings" checkbox is checked in settings.