tdd

TDD Cycle (MANDATORY)

+-----------------------------------------+
|  RED -> GREEN -> REFACTOR               |
|     ^                        |          |
|     +------------------------+          |
+-----------------------------------------+

The question is NOT "should I write tests?" but "what tests do I need?"

---

The Three Laws of TDD

1. No production code until you have a failing test
2. No more test than necessary to fail
3. No more code than necessary to pass

---

Detect Your Stack

Before starting, identify which component you're working on:

Working in	Stack	Runner	Test pattern	Details
ui/	TypeScript / React	Vitest + RTL	*.test.{ts,tsx} (co-located)	See vitest skill
prowler/	Python	pytest + moto	*_test.py (suffix) in tests/	See prowler-test-sdk skill
api/	Python / Django	pytest + django	test_*.py (prefix) in api/src/backend/**/tests/	See prowler-test-api skill

---

Phase 0: Assessment (ALWAYS FIRST)

Before writing ANY code:

UI (ui/)

# 1. Find existing tests
fd "*.test.tsx" ui/components/feature/

# 2. Check coverage
pnpm test:coverage -- components/feature/

# 3. Read existing tests

SDK (prowler/)

# 1. Find existing tests
fd "*_test.py" tests/providers/aws/services/ec2/

# 2. Run specific test
uv run pytest tests/providers/aws/services/ec2/ec2_ami_public/ -v

# 3. Read existing tests

API (api/)

# 1. Find existing tests
fd "test_*.py" api/src/backend/api/tests/

# 2. Run specific test
uv run pytest api/src/backend/api/tests/test_models.py -v

# 3. Read existing tests

Decision Tree (All Stacks)

+------------------------------------------+
|     Does test file exist for this code?  |
+----------+-----------------------+-------+
           | NO                    | YES
           v                       v
+------------------+    +------------------+
| CREATE test file |    | Check coverage   |
| -> Phase 1: RED  |    | for your change  |
+------------------+    +--------+---------+
                                 |
                        +--------+--------+
                        | Missing cases?  |
                        +---+---------+---+
                            | YES     | NO
                            v         v
                    +-----------+ +-----------+
                    | ADD tests | | Proceed   |
                    | Phase 1   | | Phase 2   |
                    +-----------+ +-----------+