This is a pytest plugin that enables you to set environment variables in the pytest.ini file.

Install with pip:

pip install pytest-env

In your pytest.ini file add a key value pair with env as the key and the environment variables as a line separated list of KEY=VALUE entries. The defined variables will be added to the environment before any tests are run:

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

Or with pyproject.toml:

[tool.pytest.ini_options]
env = [
    "HOME=~/tmp",
    "RUN_ENV=test",
]

You can use D: (default) as prefix if you don't want to override existing environment variables:

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

You can use existing environment variables using a python-like format, these environment variables will be expended before setting the environment variable:

[pytest]
env =
    RUN_PATH=/run/path/{USER}

You can apply the R: prefix to keep the raw value and skip this transformation step (can combine with the D: flag, order is not important):

[pytest]
env =
    R:RUN_PATH=/run/path/{USER}
    R:D:RUN_PATH_IF_NOT_SET=/run/path/{USER}