Test-Driven Development

Implement $ARGUMENTS using Test-Driven Development (TDD).

TDD Cycle

Repeat: Red → Green → Refactor

1. Red: Write a failing test
2. Green: Write minimal code to pass the test
3. Refactor: Clean up code (tests still pass)

Implementation Steps

Phase 1: Test Design

Confirm Requirements

• What is the input

• What is the output

• What are the edge cases

List Test Cases

• Happy path: Basic functionality
• Happy path: Boundary values
• Error case: Invalid input
• Error case: Error handling

Phase 2: Red-Green-Refactor

Step 1: Write First Test (Red)

tests/test_{module}.py

def test_{function}_basic(): """Test the most basic case""" result = function(input) assert result == expected

Run test and confirm failure:

uv run pytest tests/test_{module}.py -v

Step 2: Implementation (Green)

Write minimal code to pass the test:

• Don't aim for perfection

• Hardcoding is OK

• Just make the test pass

Run test and confirm success:

uv run pytest tests/test_{module}.py -v

Step 3: Refactoring (Refactor)

Improve while tests still pass:

• Remove duplication

• Improve naming

• Clean up structure

uv run pytest tests/test_{module}.py -v # Confirm still passes

Step 4: Next Test

Return to Step 1 with next test case from the list.

Phase 3: Completion Check

Run all tests

uv run pytest -v

Check coverage (target 80%+)

uv run pytest --cov={module} --cov-report=term-missing

Report Format

TDD Complete: {Feature Name}

Test Cases

• {test1}: {description}
• {test2}: {description} ...

Coverage

{Coverage report}

Implementation Files

• src/{module}.py: {description}
• tests/test_{module}.py: {N} tests

Notes

• Write tests first (not after)

• Keep each cycle small

• Refactor after tests pass

• Prioritize working code over perfection