timander/copilot-instructions-starter-kit/tdd

TDD Cycle

Let's implement this using test-driven development.

Before We Start

Ask:

• What behavior are we implementing?
• Can you show me an example of expected input → output?
• What's the smallest slice that would be useful?

Red Phase

Write a failing test that:

• Describes the behavior we want (test name is documentation)
• Fails for the right reason (not a syntax error)
• Is focused on one behavior

Run the test. Confirm it fails. Show the failure.

Green Phase

Write the simplest code that makes the test pass:

• No extra features
• No premature optimization
• Just enough to go green

Run the test. Confirm it passes.

Refactor Phase

Now improve the code without changing behavior:

• Remove duplication
• Improve names
• Extract if needed
• Simplify

Run the tests. Confirm they still pass.

Commit

Working, tested software. Commit before the next cycle.

What behavior should we test first?