# Test Templates & Patterns for 100% Coverage

Comprehensive reusable patterns for achieving 100% coverage across all test types and dimensions.

---

## Table of Contents

1. [Unit Test Templates](#unit-test-templates)
2. [Integration Test Templates](#integration-test-templates)
3. [E2E Test Templates](#e2e-test-templates)
4. [Performance Test Templates](#performance-test-templates)
5. [Security Test Templates](#security-test-templates)
6. [Advanced Patterns](#advanced-patterns)

---

## Unit Test Templates

### Model Unit Test Template

```python
# tests/unit/models/test_user_model.py
"""Unit tests for User model."""

import pytest
from datetime import datetime
from src.models.user import User, UserRole
from src.exceptions import ValidationError


class TestUserModel:
    """Test suite for User model."""
    
    # ============ Fixtures ============
    
    @pytest.fixture
    def valid_user_data(self):
        """Provide valid user data."""
        return {
            'email': 'test@example.com',
            'name': 'Test User',
            'password': 'SecurePassword123!',
            'role': UserRole.USER
        }
    
    @pytest.fixture
    def user(self, valid_user_data):
        """Create a test user instance."""
        return User(**valid_user_data)
    
    # ============ Creation Tests (Statement Coverage) ============
    
    def test_user_creation_with_valid_data(self, valid_user_data):
        """Test successful user creation with valid data."""
        user = User(**valid_user_data)
        assert user.email == valid_user_data['email']
        assert user.name == valid_user_data['name']
        assert user.role == valid_user_data['role']
    
    def test_user_creation_sets_default_role(self):
        """Test user creation sets default role when not specified."""
        user = User(email='test@example.com', name='Test')
        assert user.role == UserRole.USER
    
    def test_user_creation_sets_timestamps(self, valid_user_data):
        """Test user creation sets created_at and updated_at."""
        user = User(**valid_user_data)
        assert user.created_at is not None
        assert user.updated_at is not None
        assert isinstance(user.created_at, datetime)
    
    def test_user_creation_initializes_empty_projects(self, valid_user_data):
        """Test user creation initializes empty projects list."""
        user = User(**valid_user_data)
        assert user.projects == []
        assert len(user.projects) == 0
    
    # ============ Validation Tests (Branch Coverage) ============
    
    def test_user_creation_invalid_email_format(self):
        """Test user creation fails with invalid email format."""
        with pytest.raises(ValidationError) as exc_info:
            User(email='invalid-email', name='Test')
        assert 'email' in str(exc_info.value).lower()
    
    def test_user_creation_missing_email(self):
        """Test user creation fails without email."""
        with pytest.raises(ValidationError):
            User(email='', name='Test')
    
    def test_user_creation_missing_name(self):
        """Test user creation fails without name."""
        with pytest.raises(ValidationError):
            User(email='test@example.com', name='')
    
    def test_user_creation_name_too_short(self):
        """Test user creation fails with name too short."""
        with pytest.raises(ValidationError):
            User(email='test@example.com', name='A')
    
    def test_user_creation_name_too_long(self):
        """Test user creation fails with name too long."""
        long_name = 'A' * 1000
        with pytest.raises(ValidationError):
            User(email='test@example.com', name=long_name)
    
    def test_user_creation_invalid_password_too_short(self):
        """Test user creation fails with weak password."""
        with pytest.raises(ValidationError) as exc_info:
            User(email='test@example.com', name='Test', password='weak')
        assert 'password' in str(exc_info.value).lower()
    
    # ============ Password Tests (Function Coverage) ============
    
    def test_user_password_hashing(self, user):
        """Test password is hashed, not stored plain text."""
        assert user.password != 'SecurePassword123!'
        assert user.password.startswith('$2b$')  # bcrypt format
    
    def test_user_password_verification(self, user):
        """Test password verification works correctly."""
        assert user.verify_password('SecurePassword123!') is True
        assert user.verify_password('WrongPassword') is False
    
    def test_user_password_verification_case_sensitive(self, user):
        """Test password verification is case-sensitive."""
        assert user.verify_password('securepassword123!') is False
    
    def test_user_password_update(self, user):
        """Test password can be updated."""
        old_hash = user.password
        user.set_password('NewPassword123!')
        assert user.password != old_hash
        assert user.verify_password('NewPassword123!') is True
    
    # ============ Role Tests (Branch Coverage) ============
    
    def test_user_is_admin_true(self):
        """Test is_admin returns True for admin users."""
        user = User(email='test@example.com', name='Test', role=UserRole.ADMIN)
        assert user.is_admin() is True
    
    def test_user_is_admin_false(self, user):
        """Test is_admin returns False for non-admin users."""
        assert user.is_admin() is False
    
    def test_user_can_edit_self(self, user):
        """Test user can edit their own profile."""
        assert user.can_edit(user) is True
    
    def test_user_cannot_edit_other_regular(self, user):
        """Test regular user cannot edit other users."""
        other_user = User(email='other@example.com', name='Other')
        assert user.can_edit(other_user) is False
    
    def test_user_admin_can_edit_others(self):
        """Test admin can edit other users."""
        admin = User(email='admin@example.com', name='Admin', role=UserRole.ADMIN)
        other_user = User(email='other@example.com', name='Other')
        assert admin.can_edit(other_user) is True
    
    # ============ State Tests (Code Path Coverage) ============
    
    def test_user_is_active_default(self, user):
        """Test user is active by default."""
        assert user.is_active is True
    
    def test_user_deactivate(self, user):
        """Test user can be deactivated."""
        user.deactivate()
        assert user.is_active is False
    
    def test_user_activate(self, user):
        """Test user can be reactivated."""
        user.deactivate()
        user.activate()
        assert user.is_active is True
    
    def test_user_cannot_verify_password_when_inactive(self, user):
        """Test password verification fails for inactive users."""
        user.deactivate()
        with pytest.raises(PermissionError):
            user.verify_password('SecurePassword123!')
    
    # ============ String Representation Tests ============
    
    def test_user_str(self, user):
        """Test user string representation."""
        assert str(user) == 'Test User (test@example.com)'
    
    def test_user_repr(self, user):
        """Test user repr representation."""
        assert repr(user) == '<User: test@example.com>'
    
    # ============ Equality Tests ============
    
    def test_user_equality_same_email(self, user):
        """Test users with same email are equal."""
        user2 = User(email='test@example.com', name='Different Name')
        assert user == user2
    
    def test_user_inequality_different_email(self, user):
        """Test users with different email are not equal."""
        user2 = User(email='other@example.com', name='Test User')
        assert user != user2
    
    def test_user_hash_consistent(self, user):
        """Test user hash is consistent."""
        hash1 = hash(user)
        hash2 = hash(user)
        assert hash1 == hash2
    
    # ============ Boundary Value Tests ============
    
    def test_user_with_minimum_valid_values(self):
        """Test user creation with minimum valid values."""
        user = User(
            email='a@b.com',
            name='AB',
            password='ValidPass123!'
        )
        assert user.email == 'a@b.com'
        assert user.name == 'AB'
    
    def test_user_with_maximum_valid_values(self):
        """Test user creation with maximum valid values."""
        long_email = 'a' * 100 + '@' + 'b' * 100 + '.com'
        long_name = 'A' * 255
        user = User(
            email=long_email,
            name=long_name,
            password='ValidPassword123!'
        )
        assert user.email == long_email
        assert user.name == long_name
    
    # ============ Special Character Tests ============
    
    def test_user_name_with_special_characters(self):
        """Test user name with special characters."""
        user = User(
            email='test@example.com',
            name='José García-López'
        )
        assert user.name == 'José García-López'
    
    def test_user_name_with_unicode(self):
        """Test user name with unicode characters."""
        user = User(
            email='test@example.com',
            name='用户名'
        )
        assert user.name == '用户名'


# ============ Parametrized Tests (Data-Driven) ============

class TestUserValidation:
    """Parametrized validation tests for comprehensive coverage."""
    
    @pytest.mark.parametrize('email,valid', [
        ('test@example.com', True),
        ('user.name@example.co.uk', True),
        ('user+tag@example.com', True),
        ('invalid@', False),
        ('@example.com', False),
        ('test@.com', False),
        ('plainaddress', False),
    ])
    def test_email_validation(self, email, valid):
        """Test email validation with multiple formats."""
        if valid:
            user = User(email=email, name='Test')
            assert user.email == email
        else:
            with pytest.raises(ValidationError):
                User(email=email, name='Test')
    
    @pytest.mark.parametrize('password,valid', [
        ('ValidPassword123!', True),
        ('AnotherGood1!', True),
        ('weak', False),
        ('12345', False),
        ('NoNumbers!', False),
        ('nouppercasespecial1', False),
    ])
    def test_password_validation(self, password, valid):
        """Test password validation with multiple formats."""
        if valid:
            user = User(
                email='test@example.com',
                name='Test',
                password=password
            )
            assert user.verify_password(password)
        else:
            with pytest.raises(ValidationError):
                User(
                    email='test@example.com',
                    name='Test',
                    password=password
                )
```

### Service Unit Test Template

```python
# tests/unit/services/test_user_service.py
"""Unit tests for UserService."""

import pytest
from unittest.mock import Mock, MagicMock, patch, call
from datetime import datetime, timedelta
from src.services.user_service import UserService
from src.models.user import User, UserRole
from src.exceptions import (
    ValidationError, NotFoundError, DuplicateError, 
    PermissionError as PermError
)


class TestUserService:
    """Test suite for UserService."""
    
    @pytest.fixture
    def mock_db(self):
        """Provide mock database."""
        return Mock()
    
    @pytest.fixture
    def mock_event_bus(self):
        """Provide mock event bus."""
        return Mock()
    
    @pytest.fixture
    def service(self, mock_db, mock_event_bus):
        """Create service instance with mocks."""
        return UserService(
            db=mock_db,
            event_bus=mock_event_bus
        )
    
    @pytest.fixture
    def sample_user(self):
        """Create sample user object."""
        return User(
            id=1,
            email='test@example.com',
            name='Test User'
        )
    
    # ============ Create User Tests ============
    
    def test_create_user_success(self, service):
        """Test successful user creation."""
        user = service.create(
            email='new@example.com',
            name='New User',
            password='ValidPass123!'
        )
        
        assert user.email == 'new@example.com'
        assert user.name == 'New User'
        assert service.db.add.called
        assert service.db.commit.called
    
    def test_create_user_duplicate_email(self, service):
        """Test user creation fails with duplicate email."""
        service.db.user_exists.return_value = True
        
        with pytest.raises(DuplicateError):
            service.create(
                email='existing@example.com',
                name='New User'
            )
    
    def test_create_user_invalid_email(self, service):
        """Test user creation fails with invalid email."""
        with pytest.raises(ValidationError):
            service.create(
                email='invalid-email',
                name='New User'
            )
    
    def test_create_user_missing_name(self, service):
        """Test user creation fails with missing name."""
        with pytest.raises(ValidationError):
            service.create(
                email='new@example.com',
                name=''
            )
    
    def test_create_user_publishes_event(self, service):
        """Test user creation publishes event."""
        user = service.create(
            email='new@example.com',
            name='New User'
        )
        
        service.event_bus.publish.assert_called()
        event = service.event_bus.publish.call_args[0][0]
        assert event.event_type == 'user.created'
        assert event.user_id == user.id
    
    def test_create_user_sets_default_role(self, service):
        """Test user creation sets default role."""
        user = service.create(
            email='new@example.com',
            name='New User'
        )
        
        assert user.role == UserRole.USER
    
    def test_create_user_can_specify_role(self, service):
        """Test user creation can specify role."""
        user = service.create(
            email='new@example.com',
            name='New User',
            role=UserRole.ADMIN
        )
        
        assert user.role == UserRole.ADMIN
    
    # ============ Get User Tests ============
    
    def test_get_user_by_id(self, service, sample_user):
        """Test retrieving user by ID."""
        service.db.query().filter_by().first.return_value = sample_user
        
        user = service.get_by_id(1)
        
        assert user.id == 1
        assert user.email == 'test@example.com'
    
    def test_get_user_by_id_not_found(self, service):
        """Test get user by ID returns None when not found."""
        service.db.query().filter_by().first.return_value = None
        
        user = service.get_by_id(999)
        
        assert user is None
    
    def test_get_user_by_email(self, service, sample_user):
        """Test retrieving user by email."""
        service.db.query().filter_by().first.return_value = sample_user
        
        user = service.get_by_email('test@example.com')
        
        assert user.email == 'test@example.com'
    
    def test_get_user_by_email_not_found(self, service):
        """Test get user by email returns None when not found."""
        service.db.query().filter_by().first.return_value = None
        
        user = service.get_by_email('nonexistent@example.com')
        
        assert user is None
    
    # ============ Update User Tests ============
    
    def test_update_user_success(self, service, sample_user):
        """Test successful user update."""
        service.db.query().filter_by().first.return_value = sample_user
        
        updated = service.update(
            user_id=1,
            name='Updated Name'
        )
        
        assert updated.name == 'Updated Name'
        assert service.db.commit.called
    
    def test_update_user_not_found(self, service):
        """Test update non-existent user raises error."""
        service.db.query().filter_by().first.return_value = None
        
        with pytest.raises(NotFoundError):
            service.update(user_id=999, name='New Name')
    
    def test_update_user_publishes_event(self, service, sample_user):
        """Test user update publishes event."""
        service.db.query().filter_by().first.return_value = sample_user
        
        service.update(user_id=1, name='New Name')
        
        service.event_bus.publish.assert_called()
        event = service.event_bus.publish.call_args[0][0]
        assert event.event_type == 'user.updated'
    
    # ============ Delete User Tests ============
    
    def test_delete_user_success(self, service, sample_user):
        """Test successful user deletion."""
        service.db.query().filter_by().first.return_value = sample_user
        
        service.delete(user_id=1)
        
        assert service.db.delete.called
        assert service.db.commit.called
    
    def test_delete_user_not_found(self, service):
        """Test delete non-existent user raises error."""
        service.db.query().filter_by().first.return_value = None
        
        with pytest.raises(NotFoundError):
            service.delete(user_id=999)
    
    def test_delete_user_publishes_event(self, service, sample_user):
        """Test user deletion publishes event."""
        service.db.query().filter_by().first.return_value = sample_user
        
        service.delete(user_id=1)
        
        service.event_bus.publish.assert_called()
        event = service.event_bus.publish.call_args[0][0]
        assert event.event_type == 'user.deleted'
    
    # ============ List Users Tests ============
    
    def test_list_users_success(self, service):
        """Test listing all users."""
        users = [
            User(id=1, email='user1@example.com', name='User 1'),
            User(id=2, email='user2@example.com', name='User 2'),
        ]
        service.db.query().all.return_value = users
        
        result = service.list_all()
        
        assert len(result) == 2
        assert result[0].email == 'user1@example.com'
    
    def test_list_users_empty(self, service):
        """Test list users returns empty list when no users."""
        service.db.query().all.return_value = []
        
        result = service.list_all()
        
        assert result == []
        assert len(result) == 0
    
    def test_list_users_paginated(self, service):
        """Test pagination of user list."""
        users = [User(id=i, email=f'user{i}@example.com') for i in range(10)]
        service.db.query().limit().offset().all.return_value = users
        
        result = service.list_all(page=1, page_size=10)
        
        assert len(result) == 10
```

### Repository Unit Test Template

```python
# tests/unit/repositories/test_user_repository.py
"""Unit tests for UserRepository."""

import pytest
from src.repositories.user_repository import UserRepository
from src.models.user import User
from sqlalchemy.orm import Session


class TestUserRepository:
    """Test suite for UserRepository."""
    
    @pytest.fixture
    def repo(self, db_session: Session):
        """Create repository instance."""
        return UserRepository(db=db_session)
    
    def test_save_new_user(self, repo, db_session):
        """Test saving new user to database."""
        user = User(
            email='test@example.com',
            name='Test User'
        )
        
        saved = repo.save(user)
        db_session.commit()
        
        assert saved.id is not None
        assert saved.email == 'test@example.com'
    
    def test_find_by_id(self, repo, db_session):
        """Test finding user by ID."""
        user = User(email='test@example.com', name='Test')
        repo.save(user)
        db_session.commit()
        
        found = repo.find_by_id(user.id)
        
        assert found.email == 'test@example.com'
    
    def test_find_by_email(self, repo, db_session):
        """Test finding user by email."""
        user = User(email='test@example.com', name='Test')
        repo.save(user)
        db_session.commit()
        
        found = repo.find_by_email('test@example.com')
        
        assert found.name == 'Test'
    
    def test_find_by_id_not_found(self, repo):
        """Test find by ID returns None when not found."""
        found = repo.find_by_id(999)
        assert found is None
    
    def test_find_all(self, repo, db_session):
        """Test finding all users."""
        repo.save(User(email='user1@example.com', name='User 1'))
        repo.save(User(email='user2@example.com', name='User 2'))
        db_session.commit()
        
        users = repo.find_all()
        
        assert len(users) == 2
    
    def test_update_user(self, repo, db_session):
        """Test updating existing user."""
        user = User(email='test@example.com', name='Original')
        repo.save(user)
        db_session.commit()
        
        user.name = 'Updated'
        repo.save(user)
        db_session.commit()
        
        updated = repo.find_by_id(user.id)
        assert updated.name == 'Updated'
    
    def test_delete_user(self, repo, db_session):
        """Test deleting user."""
        user = User(email='test@example.com', name='Test')
        repo.save(user)
        db_session.commit()
        user_id = user.id
        
        repo.delete(user)
        db_session.commit()
        
        found = repo.find_by_id(user_id)
        assert found is None
    
    def test_exists_true(self, repo, db_session):
        """Test exists returns True when user exists."""
        repo.save(User(email='test@example.com', name='Test'))
        db_session.commit()
        
        exists = repo.exists(email='test@example.com')
        
        assert exists is True
    
    def test_exists_false(self, repo):
        """Test exists returns False when user doesn't exist."""
        exists = repo.exists(email='nonexistent@example.com')
        
        assert exists is False
    
    def test_count(self, repo, db_session):
        """Test counting users."""
        repo.save(User(email='user1@example.com', name='User 1'))
        repo.save(User(email='user2@example.com', name='User 2'))
        db_session.commit()
        
        count = repo.count()
        
        assert count == 2
```

---

## Integration Test Templates

### Service Integration Test

```python
# tests/integration/test_user_workflow.py
"""Integration tests for user-related workflows."""

import pytest
from sqlalchemy.orm import Session
from src.services.user_service import UserService
from src.models.user import User


@pytest.mark.asyncio
async def test_create_user_and_persist(db_session: Session):
    """Test creating user and persisting to database."""
    service = UserService(db=db_session)
    
    user = service.create(
        email='integration@example.com',
        name='Integration Test'
    )
    db_session.commit()
    
    # Verify persistence
    found = db_session.query(User).filter_by(
        email='integration@example.com'
    ).first()
    
    assert found is not None
    assert found.name == 'Integration Test'


@pytest.mark.asyncio
async def test_user_creation_event_integration(db_session, event_bus):
    """Test that user creation publishes event."""
    service = UserService(db=db_session, event_bus=event_bus)
    
    user = service.create(
        email='event@example.com',
        name='Event Test'
    )
    db_session.commit()
    
    # Verify event was published
    events = event_bus.get_published_events()
    user_events = [e for e in events if e.event_type == 'user.created']
    
    assert len(user_events) == 1
    assert user_events[0].user_id == user.id
```

---

## E2E Test Templates

### CLI E2E Test

```python
# tests/e2e/test_user_cli_workflow.py
"""End-to-end tests for user CLI commands."""

from click.testing import CliRunner
from src.cli.main import cli


def test_create_user_workflow():
    """Test complete user creation workflow via CLI."""
    runner = CliRunner()
    
    # Create user
    result = runner.invoke(cli, [
        'user', 'create',
        '--email', 'e2e@example.com',
        '--name', 'E2E Test User'
    ])
    
    assert result.exit_code == 0
    assert 'successfully created' in result.output
    
    # List users
    result = runner.invoke(cli, ['user', 'list'])
    
    assert result.exit_code == 0
    assert 'e2e@example.com' in result.output
    
    # Get user details
    result = runner.invoke(cli, [
        'user', 'show',
        '--email', 'e2e@example.com'
    ])
    
    assert result.exit_code == 0
    assert 'E2E Test User' in result.output


def test_error_handling_duplicate_user():
    """Test error handling when creating duplicate user."""
    runner = CliRunner()
    
    # Create first user
    runner.invoke(cli, [
        'user', 'create',
        '--email', 'duplicate@example.com',
        '--name', 'First'
    ])
    
    # Try to create duplicate
    result = runner.invoke(cli, [
        'user', 'create',
        '--email', 'duplicate@example.com',
        '--name', 'Second'
    ])
    
    assert result.exit_code != 0
    assert 'already exists' in result.output
```

---

## Performance Test Templates

### Benchmark Test

```python
# tests/performance/test_performance_benchmarks.py
"""Performance benchmark tests."""

import pytest
from src.services.user_service import UserService


@pytest.mark.benchmark
def test_create_user_performance(benchmark, service):
    """Benchmark user creation performance."""
    def create_user():
        return service.create(
            email='bench@example.com',
            name='Benchmark'
        )
    
    result = benchmark(create_user)
    assert result is not None
    # Assert completes within acceptable time
    assert benchmark.stats.mean < 0.1  # <100ms


@pytest.mark.benchmark
def test_list_large_dataset_performance(benchmark, service, db_session):
    """Benchmark listing large dataset."""
    # Create 1000 users
    for i in range(1000):
        service.create(
            email=f'user{i}@example.com',
            name=f'User {i}'
        )
    db_session.commit()
    
    def list_users():
        return service.list_all()
    
    result = benchmark(list_users)
    assert len(result) == 1000
    # Should complete in <1 second
    assert benchmark.stats.mean < 1.0
```

---

## Security Test Templates

### Security Validation Test

```python
# tests/security/test_security_validations.py
"""Security validation tests."""

import pytest
from src.models.user import User
from src.exceptions import ValidationError


def test_sql_injection_prevention():
    """Test SQL injection is prevented."""
    xss_payload = "'; DROP TABLE users; --"
    
    with pytest.raises(ValidationError):
        User(email=xss_payload, name='Test')


def test_password_not_logged():
    """Test passwords are not logged."""
    import logging
    
    with pytest.raises(AssertionError):
        user = User(email='test@example.com', name='Test', password='secret')
        # Password should not appear in logs
        assert 'secret' not in logging.getLogger().handlers[0].buffer


def test_unauthorized_access_prevented():
    """Test unauthorized access is prevented."""
    from src.auth import check_permission
    from src.models.user import UserRole
    
    user = User(email='user@example.com', name='User', role=UserRole.USER)
    admin = User(email='admin@example.com', name='Admin', role=UserRole.ADMIN)
    
    # User can't perform admin operations
    with pytest.raises(PermissionError):
        check_permission(user, 'admin.delete_user')
    
    # Admin can perform operations
    check_permission(admin, 'admin.delete_user')  # Should not raise
```

---

## Advanced Patterns

### Async Test Pattern

```python
@pytest.mark.asyncio
async def test_async_user_creation():
    """Test async user creation."""
    service = UserService()
    
    user = await service.create_async(
        email='async@example.com',
        name='Async User'
    )
    
    assert user.id is not None


@pytest.mark.asyncio
async def test_concurrent_user_creation():
    """Test concurrent user creation."""
    import asyncio
    
    service = UserService()
    
    # Create 10 users concurrently
    tasks = [
        service.create_async(
            email=f'user{i}@example.com',
            name=f'User {i}'
        )
        for i in range(10)
    ]
    
    users = await asyncio.gather(*tasks)
    assert len(users) == 10
```

### Parametrized Test Pattern

```python
@pytest.mark.parametrize('email,expected_valid', [
    ('valid@example.com', True),
    ('also.valid@example.co.uk', True),
    ('invalid@', False),
    ('@example.com', False),
])
def test_email_validation_comprehensive(email, expected_valid):
    """Parametrized test for comprehensive email validation."""
    if expected_valid:
        user = User(email=email, name='Test')
        assert user.email == email
    else:
        with pytest.raises(ValidationError):
            User(email=email, name='Test')
```

### Fixture Composition Pattern

```python
@pytest.fixture
def user_with_projects(sample_user, db_session):
    """Create user with associated projects."""
    from src.models.project import Project
    
    for i in range(5):
        project = Project(
            name=f'Project {i}',
            owner=sample_user
        )
        db_session.add(project)
    
    db_session.commit()
    return sample_user


def test_user_with_projects(user_with_projects):
    """Test user with multiple projects."""
    assert len(user_with_projects.projects) == 5
```

---

## Usage Summary

Use these templates as a starting point for comprehensive test coverage:

1. **Unit Tests**: Test individual units in isolation with mocks
2. **Integration Tests**: Test multiple components together with real DB
3. **E2E Tests**: Test complete user workflows
4. **Performance Tests**: Benchmark critical paths
5. **Security Tests**: Validate security measures

Combining these patterns will achieve **100% coverage** across all dimensions:
- ✅ Statement coverage
- ✅ Function coverage
- ✅ Branch coverage
- ✅ User story coverage
- ✅ Code path coverage

