Test-Driven Development (TDD) Workflow

Overview

Write the test first. Watch it fail. Write minimal code to pass.

Core principle: If you didn't watch the test fail, you don't know if it tests the right thing.

Violating the letter of the rules is violating the spirit of the rules.

When to Use

Always:

• New features
• Bug fixes
• Refactoring
• Behavior changes

Exceptions (ask your human partner):

• Throwaway prototypes
• Generated code
• Configuration files

Thinking "skip TDD just this once"? Stop. That's rationalization.

Session-Management Integration

Enhanced when session-management is active:

If session has "TDD" in objective or uses --tdd flag:

• Automatic RED-GREEN-REFACTOR checkpoint tracking
• Test coverage metrics in session report
• TDD cycle enforcement (blocks skipping steps)
• Session handoff includes test statistics

Works standalone without session-management - all core TDD functionality available.

The Iron Law

NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST

Write code before the test? Delete it. Start over.

No exceptions:

• Don't keep it as "reference"
• Don't "adapt" it while writing tests
• Don't look at it
• Delete means delete

Implement fresh from tests. Period.

Red-Green-Refactor

RED → Verify RED → GREEN → Verify GREEN → REFACTOR → Repeat

RED - Write Failing Test

Write one minimal test showing what should happen.

Good:

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 retryOperation(operation);

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

Clear name, tests real behavior, one thing.

Bad:

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.

Requirements:

• One behavior
• Clear name
• Real code (no mocks unless unavoidable)

Session Integration: If session-management active, I'll prompt for checkpoint label.

Verify RED - Watch It Fail

MANDATORY. Never skip.

npm test path/to/test.test.ts

Confirm:

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

Test passes? You're testing existing behavior. Fix test.

Test errors? Fix error, re-run until it fails correctly.

Session Integration: RED checkpoint automatically created with test file path.

GREEN - Minimal Code

Write simplest code to pass the test.

Good:

async function retryOperation<T>(fn: () => Promise<T>): Promise<T> {
  for (let i = 0; i < 3; i++) {
    try {
      return await fn();
    } catch (e) {
      if (i === 2) throw e;
    }
  }
  throw new Error('unreachable');
}

Just enough to pass.

Bad:

async function retryOperation<T>(
  fn: () => Promise<T>,
  options?: {
    maxRetries?: number;
    backoff?: 'linear' | 'exponential';
    onRetry?: (attempt: number) => void;
  }
): Promise<T> {
  // YAGNI - You Aren't Gonna Need It
}

Over-engineered.

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

Verify GREEN - Watch It Pass

MANDATORY.

npm test path/to/test.test.ts

Confirm:

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

Test fails? Fix code, not test.

Other tests fail? Fix now.

Session Integration: GREEN checkpoint created, cycle count incremented.

REFACTOR - Clean Up

After green only:

• Remove duplication
• Improve names
• Extract helpers

Keep tests green. Don't add behavior.

Session Integration: Optional REFACTOR checkpoint if significant changes.

Repeat

Next failing test for next feature.

Session-Management Commands

When session-management is installed and active:

Start TDD Session

# Explicit TDD session
python scripts/session.py start feature/auth --objective "Add auth (TDD)"

# Or with TDD flag
python scripts/session.py start feature/auth --tdd

Activates enhanced TDD mode with:

• Automatic checkpoint prompts
• Cycle tracking
• Test coverage monitoring
• Enforced verification steps

TDD Checkpoints

# RED checkpoint (test written, verified failing)
python scripts/session.py checkpoint --label "red-user-validation" --tdd-phase RED

# GREEN checkpoint (minimal code, test passing)
python scripts/session.py checkpoint --label "green-user-validation" --tdd-phase GREEN

# REFACTOR checkpoint (optional, when refactoring)
python scripts/session.py checkpoint --label "refactor-extract-validator" --tdd-phase REFACTOR

View TDD Metrics

# Session summary with TDD stats
python scripts/session.py status

# Shows:
# - RED-GREEN-REFACTOR cycles completed
# - Tests written vs passing
# - Average cycle time
# - Coverage trend

End TDD Session

python scripts/session.py end --handoff

Generates handoff including:

• Total TDD cycles completed
• Test files created
• Coverage metrics
• Discipline adherence (skipped verifications flagged)

Good Tests

Quality	Good	Bad
Minimal	One thing. "and" in name? Split it.	test('validates email and domain and whitespace')
Clear	Name describes behavior	test('test1')
Shows intent	Demonstrates desired API	Obscures what code should do

Why Order Matters

"I'll write tests after to verify it works"

Tests written after code pass immediately. Passing immediately proves nothing:

• Might test wrong thing
• Might test implementation, not behavior
• Might miss edge cases you forgot
• You never saw it catch the bug

Test-first forces you to see the test fail, proving it actually tests something.

"I already manually tested all the edge cases"

Manual testing is ad-hoc. You think you tested everything but:

• No record of what you tested
• Can't re-run when code changes
• Easy to forget cases under pressure
• "It worked when I tried it" ≠ comprehensive

Automated tests are systematic. They run the same way every time.

"Deleting X hours of work is wasteful"

Sunk cost fallacy. The time is already gone. Your choice now:

• Delete and rewrite with TDD (X more hours, high confidence)
• Keep it and add tests after (30 min, low confidence, likely bugs)

The "waste" is keeping code you can't trust. Working code without real tests is technical debt.

"TDD is dogmatic, being pragmatic means adapting"

TDD IS pragmatic:

• Finds bugs before commit (faster than debugging after)
• Prevents regressions (tests catch breaks immediately)
• Documents behavior (tests show how to use code)
• Enables refactoring (change freely, tests catch breaks)

"Pragmatic" shortcuts = debugging in production = slower.

"Tests after achieve the same goals - it's spirit not ritual"

No. Tests-after answer "What does this do?" Tests-first answer "What should this do?"

Tests-after are biased by your implementation. You test what you built, not what's required. You verify remembered edge cases, not discovered ones.

Tests-first force edge case discovery before implementing. Tests-after verify you remembered everything (you didn't).

30 minutes of tests after ≠ TDD. You get coverage, lose proof tests work.

Common Rationalizations

Excuse	Reality
"Too simple to test"	Simple code breaks. Test takes 30 seconds.
"I'll test after"	Tests passing immediately prove nothing.
"Tests after achieve same goals"	Tests-after = "what does this do?" Tests-first = "what should this do?"
"Already manually tested"	Ad-hoc ≠ systematic. No record, can't re-run.
"Deleting X hours is wasteful"	Sunk cost fallacy. Keeping unverified code is technical debt.
"Keep as reference, write tests first"	You'll adapt it. That's testing after. Delete means delete.
"Need to explore first"	Fine. Throw away exploration, start with TDD.
"Test hard = design unclear"	Listen to test. Hard to test = hard to use.
"TDD will slow me down"	TDD faster than debugging. Pragmatic = test-first.
"Manual test faster"	Manual doesn't prove edge cases. You'll re-test every change.
"Existing code has no tests"	You're improving it. Add tests for existing code.

Red Flags - STOP and Start Over

• Code before test
• Test after implementation
• Test passes immediately
• Can't explain why test failed
• Tests added "later"
• Rationalizing "just this once"
• "I already manually tested it"
• "Tests after achieve the same purpose"
• "It's about spirit not ritual"
• "Keep as reference" or "adapt existing code"
• "Already spent X hours, deleting is wasteful"
• "TDD is dogmatic, I'm being pragmatic"
• "This is different because..."

All of these mean: Delete code. Start over with TDD.

Example: Bug Fix

Bug: Empty email accepted

RED

test('rejects empty email', async () => {
  const result = await submitForm({ email: '' });
  expect(result.error).toBe('Email required');
});

Verify RED

$ npm test
FAIL: expected 'Email required', got undefined

GREEN

function submitForm(data: FormData) {
  if (!data.email?.trim()) {
    return { error: 'Email required' };
  }
  // ...
}

Verify GREEN

$ npm test
PASS

REFACTOR Extract validation for multiple fields if needed.

Verification Checklist

Before marking work complete:

• Every new function/method has a test
• Watched each test fail before implementing
• Each test failed for expected reason (feature missing, not typo)
• Wrote minimal code to pass each test
• All tests pass
• Output pristine (no errors, warnings)
• Tests use real code (mocks only if unavoidable)
• Edge cases and errors covered

Can't check all boxes? You skipped TDD. Start over.

When Stuck

Problem	Solution
Don't know how to test	Write wished-for API. Write assertion first. Ask your human partner.
Test too complicated	Design too complicated. Simplify interface.
Must mock everything	Code too coupled. Use dependency injection.
Test setup huge	Extract helpers. Still complex? Simplify design.

Debugging Integration

Bug found? Write failing test reproducing it. Follow TDD cycle. Test proves fix and prevents regression.

Never fix bugs without a test.

Final Rule

Production code → test exists and failed first
Otherwise → not TDD

No exceptions without your human partner's permission.

CCMP Plugin Integration

TDD workflow automatically integrates with other CCMP plugins via .ccmp/state.json:

Integration Detection (Modern API)

from lib.ccmp_integration import is_session_active, is_tdd_mode

if is_session_active():
    # Enhanced TDD mode with session integration
    pass

Legacy detection (still supported):

1. .git/sessions/<branch>/ directory exists
2. Session config has TDD objective or --tdd flag
3. session.py commands available

With session-management 🔄

Automatic activation:

python scripts/session.py start feature/auth --tdd
# → TDD workflow detects via integration API
# → Enhanced mode activates automatically

TDD metrics in sessions:

• Cycles completed tracked in session state
• Session status shows TDD discipline score
• Handoffs include test coverage metrics

With claude-context-manager 📚

Test context updates: When TDD GREEN checkpoints succeed:

• Can trigger tests/*/claude.md updates
• Documents discovered test patterns
• Keeps test strategy current

Integration example:

from lib.ccmp_integration import CCMPIntegration

integration = CCMPIntegration()
integration.update_state("tdd-workflow", {
    "active": True,
    "cycles_today": 5,
    "current_phase": "GREEN",
    "discipline_score": 100
})

If detected: Enhanced TDD mode with automatic checkpoints and metrics.

If not detected: Standard TDD guidance works perfectly standalone.

Integration Benefits

With session-management:

• 📊 Track RED-GREEN-REFACTOR cycles in session metrics
• 📍 Automatic checkpoints at each TDD phase
• 📈 Test coverage trends across session
• 🎯 TDD discipline enforcement (harder to skip steps)
• 📝 Rich handoff documents with test statistics
• ⏱️ Cycle time tracking and optimization insights

Without session-management:

• ✅ Full TDD guidance and discipline
• ✅ All core principles and workflows
• ✅ Verification checklists
• ✅ Common rationalization detection

Best of both worlds: Works great alone, better together.