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Testing Network Interface Command Correction in thefuck

A comprehensive test suite for validating network interface command corrections in the ‘thefuck’ utility. These tests ensure proper handling of device not found errors in ifconfig commands by verifying command matching and correction functionality.

Test Coverage Overview

The test suite covers error handling for network interface commands, specifically focusing on ‘Device not found’ scenarios. Key test cases include:

Validation of incorrect interface names (wlan0, eth0)
Command pattern matching for ifconfig commands
Interface name substitution logic
Error message parsing and validation

Implementation Analysis

The implementation utilizes pytest’s parametrize feature for comprehensive test case coverage. The testing approach employs fixture-based mocking of subprocess calls to simulate network interface responses, ensuring consistent and reproducible tests.

Key patterns include mock object injection, command string parsing, and output validation using pytest’s assertion framework.

Technical Details

Testing tools and configuration:

pytest framework with parametrize decorators
Mock objects for subprocess simulation
BytesIO for stdout simulation
Command type validation
Fixture-based test setup

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolation of system calls through mocking
Comprehensive positive and negative test cases
Clear test case organization using parametrization
Efficient test setup using fixtures
Explicit test case naming and organization

nvbn/thefuck

tests/rules/test_ifconfig_device_not_found.py

            
import pytest
from six import BytesIO
from thefuck.rules.ifconfig_device_not_found import match, get_new_command
from thefuck.types import Command


output = '{}: error fetching interface information: Device not found'

stdout = b'''
wlp2s0    Link encap:Ethernet  HWaddr 5c:51:4f:7c:58:5d
          inet addr:192.168.0.103  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::be23:69b9:96d2:6d39/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:23581604 errors:0 dropped:0 overruns:0 frame:0
          TX packets:17017655 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:16148429061 (16.1 GB)  TX bytes:7067533695 (7.0 GB)
'''


@pytest.fixture(autouse=True)
def ifconfig(mocker):
    mock = mocker.patch(
        'thefuck.rules.ifconfig_device_not_found.subprocess.Popen')
    mock.return_value.stdout = BytesIO(stdout)
    return mock


@pytest.mark.parametrize('script, output', [
    ('ifconfig wlan0', output.format('wlan0')),
    ('ifconfig -s eth0', output.format('eth0')),
])
def test_match(script, output):
    assert match(Command(script, output))


@pytest.mark.parametrize('script, output', [
    ('config wlan0',
     'wlan0: error fetching interface information: Device not found'),
    ('ifconfig eth0', ''),
])
def test_not_match(script, output):
    assert not match(Command(script, output))


@pytest.mark.parametrize('script, result', [
    ('ifconfig wlan0', ['ifconfig wlp2s0']),
    ('ifconfig -s wlan0', ['ifconfig -s wlp2s0']),
])
def test_get_new_comman(script, result):
    new_command = get_new_command(
        Command(script, output.format('wlan0')))
    assert new_command == result