How to pass environment variables to pytest

Question

Before I start executing the tests in my Python project, I read some environment variables and set some variables with these values read. My tests will run on the desired en

Answer 1

Run export inside a subshell (enclosing parenthesis) not to mess up local environment. Supply export with parameters from .env file.

(export $(xargs < .env); pytest -svvvx api)

Answer 2

Following the idea provided by @tutuDajuju using pytest-env - an alternative would be to write a custom plugin leveraging pytest_load_initial_conftests. Might be useful especially when you don't want or can't install external dependencies.

Here's a quick example:

Project structure

.
├── __init__.py
├── pytest.ini
├── script.py
└── tests
    ├── __init__.py
    ├── plugins
    │   ├── __init__.py
    │   └── env_vars.py
    └── test_script.py

script.py

import os

FOOBAR = os.environ.get("FOOBAR")


def foobar():
    return FOOBAR

test_script.py

from script import foobar


def test_foobar():
    assert foobar() == "foobar"

pytest.ini

[pytest]
addopts = -p tests.plugins.env_vars

env_vars.py

import os

import pytest


@pytest.hookimpl(tryfirst=True)
def pytest_load_initial_conftests(args, early_config, parser):
    os.environ["FOOBAR"] = "foobar"

Example run:

$ python -m pytest tests -v
========= test session starts =========
platform darwin -- Python 3.8.1, pytest-5.4.1, py-1.8.1, pluggy-0.13.1 -- 
rootdir: /Users/user/pytest_plugins, inifile: pytest.ini
collected 1 item

tests/test_script.py::test_foobar PASSED                                                                                               [100%]

========= 1 passed in 0.01s =========

Answer 3

In addition to other answers. There is an option to overwrite pytest_generate_tests in conftest.py and set ENV variables there.

For example, add following into conftest.py:

import os

def pytest_generate_tests(metafunc):
    os.environ['TEST_NAME'] = 'My super test name| Python version {}'.format(python_version)

This code will allow you to grab TEST_NAME ENV variable in your tests application. Also you could make a fixture:

import os
import pytest

@pytest.fixture
def the_name():
    return os.environ.get('TEST_NAME')

Also, this ENV variable will be available in your application.

Answer 4

I needed to create a pytest.ini file and pass the environment variables to the pytest command. E.g:

In the pytest.ini file I set an empty value because it is overwritten by whatever you pass to the command line command:

[pytest]
MY_ENV_VAR=

Command line, with the actual value set:

$ MY_ENV_VAR=something pytest -c pytest.ini -s tests/**

I don't know why does it work like this. I just found out that it works as a result of mere trial and error, because the other answers didn't help me.

Answer 5

1. I use monkey patch when I don't load environment variable variable outside function.

import os

# success.py
def hello_world():
    return os.environ["HELLO"]

# fail.py
global_ref = os.environ["HELLO"] # KeyError occurs this line because getting environment variable before monkeypatching

def hello_world():
    return global_ref

# test.py
def test_hello_world(monkeypatch):
    # Setup
    envs = {
        'HELLO': 'world'
    }
    monkeypatch.setattr(os, 'environ', envs)

    # Test
    result = hello_world()

    # Verify
    assert(result == 'world')

2. If you use PyCharm you can set environment variables, [Run] -> [Edit Configuration] -> [Defaults] -> [py.tests] -> [Environment Variables]

Answer 6

Another alternative is to use the pytest-env plugin. It can be configured like so:

[pytest]
env = 
    HOME=~/tmp
    D:RUN_ENV=test

the D: prefix allows setting a default value, and not override existing variables passed to py.test.

Note: you can explicitly run pytest with a custom config, if you only sometimes need to run a specialized environment set up:

pytest -c custom_pytest.ini

---

If you use PyCharm vs pytest-dotenv, this may be helpful