refactor

Safe Refactoring

Refactor: $ARGUMENTS

⚠️ Pre-Refactoring Checklist

Before ANY refactoring:

1. Verify test coverage exists

   pytest --cov=$TARGET --cov-fail-under=70 tests/
   

   If coverage < 70%, generate tests first with /test $ARGUMENTS

2. Ensure tests pass

   pytest tests/ -x
   

3. Create restore point

   git stash push -m "pre-refactor-$(date +%s)"
   

Refactoring Patterns

1. Extract Function

When: Code block is reused or does a distinct thing

# Before
def process_order(order):
    # Validate
    if not order.items:
        raise ValueError("Empty order")
    if order.total < 0:
        raise ValueError("Invalid total")
    # Process
    ...

# After  
def validate_order(order):
    """Validate order has items and valid total."""
    if not order.items:
        raise ValueError("Empty order")
    if order.total < 0:
        raise ValueError("Invalid total")

def process_order(order):
    validate_order(order)
    # Process
    ...

2. Extract Class

When: A group of functions operate on the same data

# Before: Functions scattered around
def send_email(to, subject, body): ...
def send_email_with_template(to, template, data): ...
def validate_email(email): ...

# After: Cohesive class
class EmailService:
    def send(self, to, subject, body): ...
    def send_template(self, to, template, data): ...
    def validate(self, email): ...

3. Simplify Conditionals

When: Complex if/else chains

# Before
def get_discount(user):
    if user.is_premium:
        if user.years > 5:
            return 0.25
        else:
            return 0.15
    else:
        if user.years > 5:
            return 0.10
        else:
            return 0.05

# After
DISCOUNT_MATRIX = {
    (True, True): 0.25,   # premium, 5+ years
    (True, False): 0.15,  # premium, <5 years
    (False, True): 0.10,  # standard, 5+ years
    (False, False): 0.05, # standard, <5 years
}

def get_discount(user):
    key = (user.is_premium, user.years > 5)
    return DISCOUNT_MATRIX[key]