testing-anti-patterns

# Testing Anti-Patterns

## Overview

Tests must verify real behavior, not mock behavior. Mocks are a means to isolate, not the thing being tested.

**Core principle**: Test what the code does, not what the mocks do.

**Shannon enhancement**: Automatically detect and score anti-patterns quantitatively.

**Following strict TDD prevents these anti-patterns.**

## The Iron Laws

```
1. NEVER test mock behavior
2. NEVER add test-only methods to production classes
3. NEVER mock without understanding dependencies
4. NEVER use partial/incomplete mocks
5. SHANNON: Track anti-pattern violations quantitatively
```

## Anti-Pattern 1: Testing Mock Behavior

**Severity**: 0.95/1.00 (CRITICAL)

**The violation**:
```typescript
// ❌ BAD: Testing that the mock exists
test('renders sidebar', () => {
  render(<Page />);
  expect(screen.getByTestId('sidebar-mock')).toBeInTheDocument();
});
```

**Why this is wrong**:
- You're verifying the mock works, not that the component works
- Test passes when mock is present, fails when it's not
- Tells you nothing about real behavior

**Shannon detection**:
```python
# Automatically detect mock behavior testing
def detect_mock_testing(test_code: str) -> float:
    """Returns anti-pattern score 0.00-1.00"""
    score = 0.0

    # Check for mock-specific test IDs
    if re.search(r'getByTestId.*-mock', test_code):
        score += 0.50

    # Check for assertions on mock existence only
    if 'expect(.*mock.*).toBe' in test_code and 'real assertion' not in test_code:
        score += 0.45

    return min(score, 1.0)

# Track in Serena
anti_pattern_detected = {
    "type": "testing_mock_behavior",
    "severity": 0.95,
    "test_file": test_file,
    "line": line_number,
    "recommendation": "Test real component behavior, not mock existence"
}
```

**The fix**:
```typescript
// ✅ GOOD: Test real component or don't mock it
test('renders sidebar', () => {
  render(<Page />);  // Don't mock sidebar
  expect(screen.getByRole('navigation')).toBeInThe