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Testing NPM Script Command Correction Implementation in TheFuck

This test suite validates the npm_missing_script rule in TheFuck, a command-line tool that corrects mistyped console commands. It specifically tests the functionality for correcting npm script commands when users make typing mistakes in script names.

Test Coverage Overview

The test suite provides comprehensive coverage for npm script command correction scenarios.

Key areas tested include:

Matching mistyped npm run commands
Script name suggestions for similar commands
Command correction with additional arguments
Edge cases with different command formats

Implementation Analysis

The testing approach uses pytest’s parameterized testing to validate multiple input scenarios efficiently. The implementation leverages pytest fixtures to mock npm’s script listing functionality and validates both matching conditions and command corrections.

Key patterns include:

Fixture-based dependency injection
Parameterized test cases
Mock command output handling

Technical Details

Testing tools and configuration:

pytest for test framework
BytesIO for stdout simulation
Mock objects for npm command execution
Parameterized test decorators
Custom Command type usage

Best Practices Demonstrated

The test suite demonstrates several testing best practices for command-line tool validation.

Notable practices include:

Separation of matching and correction logic
Comprehensive positive and negative test cases
Isolated test environments using fixtures
Clear test case organization
Efficient test data management

nvbn/thefuck

tests/rules/test_npm_missing_script.py

            
import pytest
from io import BytesIO
from thefuck.types import Command
from thefuck.rules.npm_missing_script import match, get_new_command

output = '''
npm ERR! Linux 4.4.0-31-generic
npm ERR! argv "/opt/node/bin/node" "/opt/node/bin/npm" "run" "dvelop"
npm ERR! node v4.4.7
npm ERR! npm  v2.15.8

npm ERR! missing script: {}
npm ERR!
npm ERR! If you need help, you may report this error at:
npm ERR!     <https://github.com/npm/npm/issues>

npm ERR! Please include the following file with any support request:
npm ERR!     /home/nvbn/exp/code_view/client_web/npm-debug.log
'''.format

run_script_stdout = b'''
Lifecycle scripts included in code-view-web:
  test
    jest

available via `npm run-script`:
  build
    cp node_modules/ace-builds/src-min/ -a resources/ace/ && webpack --progress --colors -p --config ./webpack.production.config.js
  develop
    cp node_modules/ace-builds/src/ -a resources/ace/ && webpack-dev-server --progress --colors
  watch-test
    jest --verbose --watch

'''


@pytest.fixture(autouse=True)
def run_script(mocker):
    patch = mocker.patch('thefuck.specific.npm.Popen')
    patch.return_value.stdout = BytesIO(run_script_stdout)
    return patch.return_value


@pytest.mark.parametrize('command', [
    Command('npm ru wach', output('wach')),
    Command('npm run live-tes', output('live-tes')),
    Command('npm run-script sahare', output('sahare'))])
def test_match(command):
    assert match(command)


@pytest.mark.parametrize('command', [
    Command('npm wach', output('wach')),
    Command('vim live-tes', output('live-tes')),
    Command('npm run-script sahare', '')])
def test_not_match(command):
    assert not match(command)


@pytest.mark.parametrize('script, output, result', [
    ('npm ru wach-tests', output('wach-tests'), 'npm ru watch-test'),
    ('npm -i run-script dvelop', output('dvelop'),
     'npm -i run-script develop'),
    ('npm -i run-script buld -X POST', output('buld'),
     'npm -i run-script build -X POST')])
def test_get_new_command(script, output, result):
    command = Command(script, output)

    assert get_new_command(command)[0] == result