Testing Click Applications with Pytest

README.md

Requirements

• Python 3.6
• pip
• virtualenvwrapper

Instructions

Copy these files into a directory. Run the tests.

mkvirtualenv greet && pip install -e .'[dev]' && pytest -v

dev-requirements.txt

pytest==3.1.3

greet.py

import sys

import click


@click.command()
@click.version_option()
@click.option('--count', default=1, show_default=True, help='Number of greetings')
@click.option('--name', prompt='Your name', help='The person to greet.')
@click.option('--debug', is_flag=True, show_default=True)
def cli(count: int, name: str, debug: bool) -> None:
    if debug:
        msg = f"[DEBUG] Printing greeting {count} times for {name}."
        click.echo(msg, file=sys.stderr)

    for _ in range(count):
        click.echo(f"Hello, {name}!")

requirements.txt

click==6.7

setup.py

import os.path
from setuptools import setup, find_packages
from pip.req import parse_requirements

root = os.path.abspath(os.path.dirname(__file__))

req_path = os.path.join(root, 'requirements.txt')
reqs = [str(r.req) for r in parse_requirements(req_path, session=False)]

dev_req_path = os.path.join(root, 'dev-requirements.txt')
dev_reqs = [str(r.req) for r in parse_requirements(dev_req_path, session=False)]

setup(
    name='greet',
    version='0.1.0',
    description='A greeter.',
    author='Reilly Tucker Siemens',
    packages=find_packages(),
    include_package_data=True,
    install_requires=reqs,
    extras_require={
        'dev': dev_reqs,
    },
    entry_points={
        'console_scripts': [
            'greet=greet:cli',
        ]
    }
)

test_greet.py

from click.testing import CliRunner
import pytest

import greet


def test_greet_no_options():
    """greet should prompt the user for their name given no options."""
    runner = CliRunner()
    result = runner.invoke(greet.cli, input='John Cleese')
    assert not result.exception
    assert result.output == 'Your name: John Cleese\nHello, John Cleese!\n'


@pytest.mark.parametrize('name', [
    '',
    'John Cleese',
    '松本 人志',
    'New\nLine',
])
def test_greet_with_name(name):
    """greet --name should not prompt for a name and use the given value."""
    runner = CliRunner()
    result = runner.invoke(greet.cli, ['--name', name])
    assert result.output == f"Hello, {name}!\n"


@pytest.mark.parametrize('count', [
    '-1',
    '0',
    '1',
    '2',
    '3',
    '100',
])
def test_greet_with_count(count):
    """greet --count should output the greeting count times."""
    runner = CliRunner()
    result = runner.invoke(greet.cli, ['--count', count], input='John Cleese')
    greetings = "Hello, John Cleese!\n" * int(count)
    assert result.output == f"Your name: John Cleese\n{greetings}"


@pytest.mark.parametrize('name, count', [
    ('John Cleese', '5'),
    ('松本 人志', '10'),
])
def test_greet_with_name_and_count(name, count):
    """greet should work when given both --name and --count."""
    runner = CliRunner()
    result = runner.invoke(greet.cli, ['--name', name, '--count', count])
    assert result.output == f"Hello, {name}!\n" * int(count)

def test_greet_shows_debug_info_in_debug_mode():
    runner = CliRunner()
    result = runner.invoke(greet.cli, ['--name', 'John Cleese', '--debug'])
    assert result.output == ('[DEBUG] Printing greeting 1 times for John '
                             'Cleese.\nHello, John Cleese!\n')