tdd-vitest-typescript

Erwartetes Ergebnis:

## TDD Approach: User Registration

### 1. Red - Write Failing Test

```typescript
describe('User Registration', () => {
it('creates new user account with valid email', async () => {
const result = await registerUser({
email: 'new@example.com',
password: 'secure123',
});

expect(result.success).toBe(true);
expect(result.user.email).toBe('new@example.com');
});

it('rejects registration with existing email', async () => {
// ... test for duplicate email handling
});

it('rejects weak passwords', async () => {
// ... test for password validation
});
});
```

### 2. Green - Minimal Implementation

Write just enough code to pass the tests.

### 3. Refactor

Improve the implementation while keeping tests green.

Erwartetes Ergebnis:

## Vitest + TypeScript Setup

### Install Dependencies
```bash
npm install -D vitest @vitest/ui @vitest/coverage-v8 typescript @types/node
```

### Create vitest.config.ts
```typescript
import { defineConfig } from 'vitest/config';

export default defineConfig({
test: {
globals: true,
environment: 'node',
coverage: {
provider: 'v8',
reporter: ['text', 'json', 'html'],
},
},
});
```

### Configure tsconfig.json
```json
{
"compilerOptions": {
"types": ["vitest/globals", "node"],
"esModuleInterop": true,
"strict": true
}
}
```