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Testing Script Existence Detection Rules in TheFuck Command-Line Tool

This test suite validates the functionality of the ‘has_exists_script’ rule in TheFuck project, which handles cases where commands exist as scripts in the current directory but aren’t properly invoked with ‘./’.

Test Coverage Overview

The test suite provides comprehensive coverage for the script existence checking functionality.

Key areas tested include:

Command not found scenarios with existing scripts
Command not found scenarios with non-existing scripts
Command variations with arguments (–help)
Empty output handling

Implementation Analysis

The testing approach utilizes Python’s mock library to simulate file system behaviors, specifically patching os.path.exists.

Testing patterns include:

Context manager usage for mock implementation
Multiple assertion scenarios within single test functions
Positive and negative test cases

Technical Details

Testing tools and configuration:

Python mock library for path existence simulation
Command type from thefuck.types for input structuring
Pytest as the testing framework
Patch decorator for mock implementation

Best Practices Demonstrated

The test suite demonstrates several testing best practices in Python.

Notable practices include:

Isolation of system dependencies through mocking
Clear test function naming and organization
Comprehensive positive and negative test cases
Efficient test case grouping within functions

nvbn/thefuck

tests/rules/test_has_exists_script.py

            
from mock import patch
from thefuck.rules.has_exists_script import match, get_new_command
from thefuck.types import Command


def test_match():
    with patch('os.path.exists', return_value=True):
        assert match(Command('main', 'main: command not found'))
        assert match(Command('main --help',
                             'main: command not found'))
        assert not match(Command('main', ''))

    with patch('os.path.exists', return_value=False):
        assert not match(Command('main', 'main: command not found'))


def test_get_new_command():
    assert get_new_command(Command('main --help', '')) == './main --help'