# Calculator CLI - Tasks for Webber

A simple calculator with intentional bugs and missing features for testing Webber's capabilities.

## Bugs to Fix

### High Priority
- [ ] **Division by zero** - `operations.py:divide()` crashes when dividing by zero instead of returning an error
- [ ] **Invalid operation name** - `main.py:get_operation()` raises KeyError for unknown operations instead of helpful error message

### Medium Priority
- [ ] **Power function broken** - `operations.py:power()` doesn't handle negative exponents or fractional exponents correctly
- [ ] **No input validation** - `main.py` doesn't validate that command-line arguments are valid numbers

## Missing Tests

- [ ] Add `TestDivide` class with tests for:
  - Normal division
  - Division by zero (should test error handling once bug is fixed)
  - Division with negative numbers

- [ ] Add `TestPower` class with tests for:
  - Positive integer exponents
  - Zero exponent (should return 1)
  - Negative exponents

- [ ] Complete existing test classes:
  - `test_add_zero`
  - `test_add_floats`
  - `test_subtract_negative`
  - `test_multiply_by_zero`

## Features to Add

- [ ] **Expose power operation** - Add 'pow' to the operations dictionary in `main.py`
- [ ] **Add modulo operation** - Implement `modulo(a, b)` in operations.py
- [ ] **Add --verbose flag** - Show step-by-step calculation
- [ ] **Add history command** - Track and display recent calculations
- [ ] **Add REPL mode** - Interactive calculator loop

## Code Quality

- [ ] Add type hints to all functions
- [ ] Add docstrings following Google style
- [ ] Fix any linting errors (run `ruff check src/`)

## How to Run

```bash
# Setup
python3.12 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

# Run calculator
python -m calculator.main 10 5 add
python -m calculator.main 10 5 div

# Run tests
pytest tests/ -v

# See failing tests (division by zero)
python -m calculator.main 10 0 div
```