What is Pytest Shell Utilities

"When in doubt, shell out"

—Thomas S. Hatch

This pytest plugin was extracted from pytest-salt-factories. If provides a basic fixture shell which basically uses subprocess.Popen to run commands against the running system on a shell while providing a nice assert'able return class.

Install

Installing pytest-shell-utilities is as simple as:

python -m pip install pytest-shell-utilities

And, that's honestly it.

Usage

Once installed, you can now use the shell fixture to run some commands and assert against the outcome.

def test_assert_good_exitcode(shell):

    ret = shell.run("exit", "0")
    assert ret.returncode == 0


def test_assert_bad_exitcode(shell):

    ret = shell.run("exit", "1")
    assert ret.returncode == 1

If the command outputs parseable JSON, the shell fixture can attempt loading that output as JSON which allows for asserting against the JSON loaded object.

def test_against_json_output(shell):
    d = {"a": "a", "b": "b"}
    ret = shell.run("echo", json.dumps(d))
    assert ret.data == d

Additionally, the return object's .stdout and .stderr can be line matched using pytest.pytester.LineMatcher:

MARY_HAD_A_LITTLE_LAMB = """\
Mary had a little lamb,
Its fleece was white as snow;
And everywhere that Mary went
The lamb was sure to go.
"""


def test_matcher_attribute(shell):
    ret = shell.run("echo", MARY_HAD_A_LITTLE_LAMB)
    ret.stdout.matcher.fnmatch_lines_random(
        [
            "*had a little*",
            "Its fleece was white*",
            "*Mary went",
            "The lamb was sure to go.",
        ]
    )

Documentation

The full documentation can be seen here.