/impl - TDD Development Command

This command follows Kent Beck's TDD methodology. Strictly adheres to the RED→GREEN→REFACTOR cycle with a test-first approach.

Integrated commands: Uses /check and /review internally.

Usage

/impl Add validation to login form
/impl  # Start interactively

[1/4] Task Preparation

Get Task Description

• •If $ARGUMENTS exists: Use as-is
• •If empty: Ask with AskUserQuestion

Check Existing Documents

Check for docs/DESIGN.md and docs/TODO.md using Read tool.

If docs/TODO.md exists:

• •Read content and understand phase structure
• •Check RED/GREEN/REFACTOR tasks in each phase

TODO.md structure example:

### Phase 1: Implement version calculation

- [ ] [RED] Write test for calculate_latest
- [ ] [GREEN] Implement calculate_latest
- [ ] [REFACTOR] Refactor calculate_latest

[2/4] Phase Execution

Manage Tasks with TodoWrite

Manage current phase tasks with TodoWrite.

RED-GREEN-REFACTOR Cycle

RED (Write Test)

1. •Update TodoWrite to in_progress
2. •Write test based on expected input/output
3. •Run /check --test, confirm failure
4. •Commit on failure (proves test is correct)
5. •Update TodoWrite to completed

GREEN (Implement)

1. •Update TodoWrite to in_progress
2. •Write minimal implementation to pass test
3. •Run /check --test, confirm success
4. •Update TodoWrite to completed

REFACTOR

1. •Update TodoWrite to in_progress
2. •Improve code quality following design principles
3. •Run /check --test, maintain success
4. •Update TodoWrite to completed

Design Principles Checklist:

[3/4] Phase Approval

After completing all RED/GREEN/REFACTOR tasks in phase:

Step 1: Self Review

Run /review --uncommitted --brief:

Review changed files.
Report Critical/Warning issues only.

If issues found:

1. •Fix issues
2. •Confirm success with /check --test
3. •Run self review again
4. •Repeat until no issues

Step 2: Quality Check

Run /check:

# Run all checks (lint, format, build, test)

On failure:

1. •Fix issues
2. •Run /check again
3. •Repeat until passed

Step 3: Phase Completion

Ask for approval with AskUserQuestion:

Phase X completed.

Implemented:
- [Features implemented]

Changed files:
- [File list]

Test results: X tests passed
Review results: PASSED

Proceed to next phase?

[4/4] Completion

Completion Summary

✓ Development completed

Implemented:
- [List of features/fixes]

Created/Modified files:
- [File path list]

Test results:
- X tests passed

Quality checks:
- lint: PASSED
- format: PASSED
- build: PASSED

Next Action

Ask with AskUserQuestion:

• •Commit: Run /conventional-commit
• •Done: End development

TDD Absolute Rules

1. •Never write code without tests
2. •Follow RED→GREEN→REFACTOR cycle
3. •Minimal implementation - Only code to pass current test
4. •Refactor only when GREEN
5. •Commit on RED - Proves test is correct

Anti-patterns

• •Write tests "later"
• •Implement before writing tests
• •Refactor when RED
• •Implement multiple phases simultaneously
• •Skip quality checks