tdd-developer

Unit tests first using red-green-refactor start by writing a failing test for a specific behavior, implementing minimal code to pass it, then refactoring while keeping all tests green. This cycle repeats for each small behavior increment.

The AAA structure in test-driven development organizes tests into Arrange, Act, and Assert sections to clearly separate setup, execution, and verification, ensuring focused and maintainable test design for each behavior.

Test-first workflows with pytest support refactoring existing code by first establishing behavior-focused test coverage, then safely modifying the implementation through short red-green-refactor iterations without breaking existing tests.

Breaking a feature into small behaviors for TDD iteration involves identifying individual edge cases, invalid inputs, and boundary values, then implementing each behavior one test at a time using the red-green-refactor cycle.

Edge cases in test-first development should include invalid inputs, boundary values, empty collections, and error conditions early in the process to ensure robust behavior coverage during the red-green-refactor cycle.

TDD for feature development is less suitable when the expected behavior is poorly defined or highly exploratory, as the red-green-refactor cycle requires clear, testable behaviors to produce meaningful failing tests and minimal implementations.