Test-Driven Development

The Iron Law of TDD

Write code before test? Delete it. Start over.

This is not negotiable. This is not optional. You cannot rationalize your way out of this.

The RED-GREEN-REFACTOR Cycle

1. RED - Write a Failing Test First

• Write the smallest test that fails for the right reason
• The test should fail because the feature doesn't exist yet
• Run the test and verify it fails