1. Write failing tests (RED phase)

2. Verify the test fails due to the behavior of the application, and NOT due to the test. If you have more than one test that you need to write, you should write all of them before moving to the GREEN phase.

3. Write the minimal amount of code necessary to make the test pass (GREEN phase)

4. Verify the test now passes due to the behavior of the application.

   • If you go through three loops without making progress, switch to running /home/dom/Downloads/repos/zipper/.claude/skills/creating-debug-tests-and-iterating

5. Refactor the code to clean it up.

6. Verify tests still pass.

RED - Write Failing Test

Write one minimal test showing what should happen.

test('retries failed operations 3 times', async () => {
  let attempts = 0;
  const operation = () => {
    attempts++;
    if (attempts < 3) throw new Error('fail');
    return 'success';
  };

  const result = await foobar.retryOperation(operation);

  expect(result).toBe('success');
  expect(attempts).toBe(3);
});

Clear name, tests real behavior, one thing. Note that the tested operation is imported -- this is a STRONG sign that this is testing something real.

test('retry works', async () => {
  const mock = jest
    .fn()
    .mockRejectedValueOnce(new Error())
    .mockRejectedValueOnce(new Error())
    .mockResolvedValueOnce('success');
  await retryOperation(mock);
  expect(mock).toHaveBeenCalledTimes(3);
});

Vague name, tests mock not code

Verify RED - Watch It Fail

npm test path/to/test.test.ts

Confirm:

• Test fails (not errors)
• Failure message is expected
• Fails because feature missing (not typos)

GREEN - Minimal Code

Write simplest code to pass the test.

Don't add features, refactor other code, or "improve" beyond the test.

Verify GREEN - Watch It Pass

npm test path/to/test.test.ts

Confirm:

• Test passes
• Other tests still pass
• Output pristine (no errors, warnings)

REFACTOR - Clean Up

After green only:

• Remove duplication
• Improve names
• Extract helpers

Keep tests green. Do not add behavior.