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Testing Brew Formula Update Command Correction in TheFuck

This test suite validates the brew_update_formula rule in TheFuck, a command-line tool that corrects mistyped console commands. The tests ensure proper handling of brew update/upgrade commands and their error corrections.

Test Coverage Overview

The test suite provides comprehensive coverage of the brew_update_formula rule functionality, focusing on command correction scenarios.

Tests matching logic for incorrect brew update usage
Validates command transformation from update to upgrade
Covers multiple formula name variations
Handles both single and multiple formula cases

Implementation Analysis

The implementation uses pytest’s parametrize feature to efficiently test multiple input scenarios. The testing approach focuses on command pattern matching and transformation verification.

Uses Command object pattern for input/output handling
Implements parametrized test cases for varied inputs
Separates matching and command generation logic

Technical Details

Framework: pytest
Test Types: Unit tests
Key Components: Command class, match function, get_new_command function
Error Message Handling: Validates specific brew error output

Best Practices Demonstrated

The test suite exemplifies several testing best practices in Python unit testing.

Clear test function naming conventions
Effective use of pytest.mark.parametrize for test case variations
Separate positive and negative test cases
Consistent assertion patterns

nvbn/thefuck

tests/rules/test_brew_update_formula.py

            
import pytest
from thefuck.types import Command
from thefuck.rules.brew_update_formula import get_new_command, match


output = ("Error: This command updates brew itself, and does not take formula"
          " names.
Use `brew upgrade thefuck`.")


def test_match():
    command = Command('brew update thefuck', output)
    assert match(command)


@pytest.mark.parametrize('script', [
    'brew upgrade foo',
    'brew update'])
def test_not_match(script):
    assert not match(Command(script, ''))


@pytest.mark.parametrize('script, formula, ', [
    ('brew update foo', 'foo'),
    ('brew update bar zap', 'bar zap')])
def test_get_new_command(script, formula):
    command = Command(script, output)
    new_command = 'brew upgrade {}'.format(formula)
    assert get_new_command(command) == new_command