test-driven-development

Test-driven development prevents regressions by enforcing a RED-GREEN-REFACTOR workflow, requiring you to write a failing test that verifies intended behavior before implementing minimal production code to make it pass.

The red-green-refactor cycle is a unit testing workflow where you write a failing test, implement the smallest code to make it pass, and then refactor safely while running targeted and full test suites to prevent regressions.

Fix bugs using test-first development by writing a failing test that verifies the intended behavior, implementing the minimal production code to make the test pass, and re-running the full test suite to ensure no regressions.

Test-driven development works for refactoring by driving the RED-GREEN-REFACTOR workflow, allowing you to safely change behavior while verification discipline ensures tests pass without warnings or other test breakages.

Unit tests focus on the wrong behavior when relying on mocks or implementation details; behavior-first quality reduces testing the wrong thing by focusing tests on real code behavior to ensure proper verification.

Pytest supports strict test-driven development workflows by enabling you to write failing tests first, verify they fail for the right reason, implement minimal code to pass, and run the full test suite to confirm no regressions.