# Scout MCP Testing Evaluation Report
**Date:** 2025-12-07
**Status:** Comprehensive Analysis
**Coverage Target:** 85%+
**Current State:** Well-structured with critical gaps in Phase 2 requirements
---
## Executive Summary
Scout MCP has **148 tests** (~5,856 lines) covering a well-structured codebase (~3,570 lines). The test pyramid is reasonably balanced with good unit and integration test coverage. However, **critical security and performance test gaps** exist that directly block Phase 2 requirements.
| Metric | Value | Status |
|--------|-------|--------|
| **Total Tests** | 148 | ✓ Good |
| **Test Lines** | ~5,856 | ✓ Good |
| **Source Lines** | ~3,570 | ✓ Good |
| **Test/Code Ratio** | 1.64:1 | ✓ Good |
| **Coverage** | ~65-75% (estimated) | ⚠ Moderate |
| **Critical Gaps** | 12 scenarios | ✗ Blocking |
---
## Part 1: Test Coverage Analysis
### Current Test Distribution
```
Tests by Category:
├── Unit Tests (~85 tests, 57%)
│ ├── test_executors.py - SSH command execution
│ ├── test_validation.py - Input validation
│ ├── test_security.py - Shell quoting, injection prevention
│ ├── test_pool.py - Connection pool basic operations
│ ├── test_config.py - SSH config parsing
│ └── test_connection.py - SSH connection management
│
├── Integration Tests (~35 tests, 24%)
│ ├── test_integration.py - End-to-end flows
│ ├── test_server_lifespan.py - Server lifecycle
│ ├── test_beam_integration.py - File transfer operations
│ ├── test_scout.py - Scout tool handler
│ └── test_middleware/test_*.py - Middleware stack
│
├── Performance Tests (~20 tests, 14%)
│ ├── test_pool_concurrency.py - Concurrent operations
│ ├── test_pool_limits.py - LRU eviction, size limits
│ └── benchmarks/ - Performance profiling
│
└── Specialized Tests (~8 tests, 5%)
├── test_health.py - Health endpoint
├── test_ping.py - Host availability checks
└── test_module_structure.py - Import verification
```
### Coverage by Module (Estimated)
| Module | Files | Coverage | Status |
|--------|-------|----------|--------|
| `utils/` | validation.py, shell.py, transfer.py, hostname.py | 85-90% | ✓ Good |
| `services/` | executors.py, pool.py, connection.py, state.py | 70-80% | ⚠ Gaps |
| `tools/` | scout.py, handlers.py | 60-70% | ⚠ Gaps |
| `middleware/` | auth.py, ratelimit.py, logging.py, timing.py | 75-85% | ✓ Good |
| `resources/` | compose.py, docker.py, hosts.py, zfs.py | 50-60% | ✗ Low |
| `models/` | ssh.py, command.py, target.py, broadcast.py | 80-90% | ✓ Good |
### Largest Test Files (by Line Count)
| File | Lines | Focus | Quality |
|------|-------|-------|---------|
| `test_server_lifespan.py` | 351 | Server lifecycle, initialization | High |
| `test_logging.py` | 325 | Middleware logging integration | High |
| `test_integration.py` | 328 | End-to-end tool flows | High |
| `test_ratelimit.py` | 210 | Rate limiting edge cases | High |
| `test_security.py` | 226 | Shell injection prevention | High |
| `test_validation.py` | 251 | Path/host validation | High |
| `test_config.py` | 285 | SSH config parsing | High |
---
## Part 2: Test Pyramid Assessment
### Current Distribution
```
△ (E2E/Integration)
/ \
/ \ ~35 tests (24%)
/ \
/-------\
/ \ ~85 tests (57%)
/ UNIT \
/-----------\
/ \ ~20 tests (14%)
/ PERFORMANCE \ (pool, concurrency)
/_______________\
~8 tests (5%)
SPECIALIZED
```
**Assessment:** WELL-BALANCED pyramid. Inverted from ideal but appropriate for library code.
- ✓ Strong unit test foundation (57%)
- ✓ Solid integration coverage (24%)
- ✓ Dedicated performance testing (14%)
- ⚠ Limited E2E (user scenario) testing
### Pyramid Compliance
| Level | Count | Quality | Gap |
|-------|-------|---------|-----|
| **Unit** | 85 | High (mocked dependencies) | ✓ Covered |
| **Integration** | 35 | High (real pool/connections) | ✓ Covered |
| **E2E** | ~10 | Medium (limited scenarios) | ⚠ Gaps |
| **Performance** | 20 | Good (timing validation) | ✓ Covered |
---
## Part 3: Critical Path Testing
### Connection Pooling (Pool.py)
**Tests Present:**
- ✓ `test_pool.py`: 152 lines, 8 tests
- Connection creation
- Connection reuse
- Closed connection replacement
- Pool cleanup
- Idle timeout handling
- ✓ `test_pool_limits.py`: 193 lines, 7 tests
- LRU eviction when full
- Eviction updates LRU order
- Pool size limits (max=100 default)
- Eviction closes connections properly
- ✓ `test_pool_concurrency.py`: 163 lines, 8 tests
- Concurrent different hosts (parallel execution)
- Concurrent same host (serialization)
- Three concurrent hosts
- Mixed concurrent access patterns
- Sequential then concurrent mixing
- Cleanup during concurrent access
**Coverage Assessment:** 85-90%
**Gap Severity:** LOW - Core pooling logic well-tested
**Missing Scenarios:**
- [ ] Pool with actual asyncssh connections (not mocked)
- [ ] Connection pool exhaustion recovery (all 100 connections in use)
- [ ] Pool cleanup timing precision (verify 60s idle timeout)
- [ ] Memory usage validation with 100 connections (~20MB target)
---
### Singleton Initialization Race Conditions (SEC-005)
**Tests Present:**
- ✓ `test_server_lifespan.py`: Limited coverage of startup
- ⚠ No dedicated concurrency tests for singleton initialization
**Coverage Assessment:** 30-40%
**Gap Severity:** HIGH - BLOCKING Phase 2 requirement
**Specific Gaps:**
- [ ] `test_concurrent_singleton_initialization()` - 100 concurrent get_config() calls
- [ ] `test_race_condition_pool_creation()` - Multiple threads initializing pool
- [ ] `test_singleton_reset_concurrency()` - Concurrent reset() calls
- [ ] `test_singleton_isolation()` - Verify per-test isolation
**Example Missing Test:**
```python
@pytest.mark.asyncio
async def test_concurrent_singleton_initialization():
"""SEC-005: Verify singleton thread-safety with concurrent access."""
from scout_mcp.services import reset_state, get_config
reset_state() # Start fresh
# 100 concurrent initializations
configs = await asyncio.gather(*[
asyncio.to_thread(get_config)
for _ in range(100)
])
# All should get the SAME instance
assert len(set(id(c) for c in configs)) == 1
assert configs[0] is configs[99]
```
---
### Authentication & Authorization
**Tests Present:**
- ✓ `test_middleware/test_auth.py`: 176 lines, 10+ tests
- Health endpoint auth bypass
- Missing API key (401)
- Invalid API key (401)
- Valid key first in list
- Valid key second in list
- Auth disabled (no keys)
- Auth disabled (explicit)
**Coverage Assessment:** 80-85%
**Gap Severity:** MEDIUM - Missing per-user ACLs
**Specific Gaps (SEC-003: No Resource-Level Authorization):**
- [ ] `test_no_resource_level_authorization()` - Verify no per-user ACLs enforced
- [ ] `test_all_hosts_visible_to_all_users()` - Confirm no filtering
- [ ] `test_resource_access_no_checks()` - Verify resources aren't filtered
**Example Missing Test:**
```python
def test_no_resource_level_authorization():
"""SEC-003: Verify no resource-level authorization implemented."""
from scout_mcp.resources import scout_resource, list_hosts_resource
# Should not have authorization checks
assert not hasattr(scout_resource, '_authorized_users')
assert not hasattr(list_hosts_resource, '_authorized_users')
# Should return all hosts regardless of user
hosts1 = list_hosts_resource() # "user1"
hosts2 = list_hosts_resource() # "user2"
assert len(hosts1) == len(hosts2) # Same hosts visible
```
---
### Input Validation (Security-Critical)
**Tests Present:**
- ✓ `test_validation.py`: 251 lines, 30+ tests
- Path traversal (../ injection)
- Null bytes
- Empty paths/hosts
- Special characters handling
- IP addresses
- Command injection characters (;|&$`)
- 253-char hostname max
- ✓ `test_security.py`: 226 lines, 15+ tests
- Shell quoting (shlex.quote)
- Injection attempt protection
- Backtick escaping
- Dollar expansion safety
- Semicolon injection prevention
- Pipe injection prevention
- Ampersand backgrounding prevention
- Newline handling
**Coverage Assessment:** 85-90%
**Gap Severity:** LOW - Well-tested
**Edge Cases Still Uncovered:**
- [ ] Unicode path normalization attacks
- [ ] Symlink traversal (follows symlinks to escape)
- [ ] Very long paths (>4096 chars)
- [ ] TOCTOU race conditions (path changes between validation and use)
---
### SSH Host Key Verification
**Tests Present:**
- ⚠ Minimal explicit testing
- `test_pool.py` mocks with `SCOUT_KNOWN_HOSTS=none`
**Coverage Assessment:** 20-30%
**Gap Severity:** MEDIUM - Security feature needs validation
**Specific Gaps:**
- [ ] `test_known_hosts_verification()` - Verify host key checking
- [ ] `test_unknown_host_rejected_strict()` - Strict mode rejection
- [ ] `test_unknown_host_warning_nonstrict()` - Non-strict warning
- [ ] `test_known_hosts_file_missing()` - Fallback behavior
**Example Missing Test:**
```python
@pytest.mark.asyncio
async def test_known_hosts_verification(monkeypatch, tmp_path):
"""Test that SSH host key verification is enforced."""
known_hosts = tmp_path / "known_hosts"
known_hosts.write_text("testhost ssh-rsa AAAAB3...")
monkeypatch.setenv("SCOUT_STRICT_HOST_KEY_CHECKING", "true")
monkeypatch.setenv("SCOUT_KNOWN_HOSTS", str(known_hosts))
pool = ConnectionPool(idle_timeout=60, known_hosts=str(known_hosts))
host = SSHHost(name="unknown", hostname="unknown.local", user="test", port=22)
# Should fail - host key not in known_hosts
with pytest.raises(asyncssh.KeyImportError):
await pool.get_connection(host)
```
---
### Rate Limiting
**Tests Present:**
- ✓ `test_middleware/test_ratelimit.py`: 210 lines, 12+ tests
- Token bucket algorithm
- Normal traffic allowed
- Burst exceeded detection
- Health endpoint bypass
- Disabled rate limiting
- Per-client isolation
- X-Forwarded-For header support
- Retry-After header
**Coverage Assessment:** 80-85%
**Gap Severity:** LOW - Well-tested
**Edge Cases Uncovered:**
- [ ] Rate limit precision (<10μs overhead verification)
- [ ] Concurrent burst consumption race conditions
- [ ] Clock skew handling
- [ ] Memory usage with 10K+ clients
---
## Part 4: Security & Phase 2 Requirement Testing
### Requirement Matrix
| Req | Requirement | Tests | Coverage | Status |
|-----|-------------|-------|----------|--------|
| SEC-001 | Auth disabled by default | ✓ test_auth.py | 90% | ✓ Good |
| SEC-002 | Bind to 0.0.0.0 by default | ⚠ test_server_lifespan.py | 40% | ⚠ Gaps |
| SEC-003 | No resource-level ACLs | ✗ None | 0% | ✗ MISSING |
| SEC-004 | No audit logging | ⚠ Implicit | 0% | ✗ MISSING |
| SEC-005 | Singleton race condition | ⚠ Implicit | 20% | ✗ MISSING |
| SEC-007 | Health endpoint auth bypass | ✓ test_auth.py | 95% | ✓ Good |
### Security Test Gaps (BLOCKING Phase 2)
#### 1. SEC-002: Network Binding Validation
**Current State:** Assumed behavior, not tested
**Priority:** P1 - Network security
**Lines of Code to Test:** 3-5
```python
@pytest.mark.asyncio
async def test_binds_to_0_0_0_by_default(monkeypatch):
"""SEC-002: Verify server binds to 0.0.0.0 by default."""
monkeypatch.delenv("SCOUT_HTTP_HOST", raising=False)
from scout_mcp.server import create_http_server
# Should use 0.0.0.0 by default
config = get_config()
assert config.http_host == "0.0.0.0"
# Verify actual binding
server = create_http_server(config)
# Should be listening on all interfaces
assert "0.0.0.0" in str(server.sockets)
@pytest.mark.asyncio
async def test_can_bind_to_localhost(monkeypatch):
"""SEC-002: Verify server can be restricted to localhost."""
monkeypatch.setenv("SCOUT_HTTP_HOST", "127.0.0.1")
config = get_config()
assert config.http_host == "127.0.0.1"
```
#### 2. SEC-003: No Resource-Level Authorization
**Current State:** Not implemented, not tested
**Priority:** P1 - Access control
**Lines of Code to Test:** 5-10
```python
def test_no_resource_level_authorization():
"""SEC-003: Confirm no per-user resource filtering implemented."""
from scout_mcp.resources import scout_resource, list_hosts_resource
from scout_mcp.config import Config
config = get_config()
hosts = config.get_hosts()
# Resources should NOT filter by user
# All users should see all hosts
for _ in range(3): # Simulate 3 different "users"
visible_hosts = config.get_hosts() # No user parameter
assert len(visible_hosts) == len(hosts)
# Should be able to read any host
for host in hosts:
conn = pool.get_connection(host) # No auth check
def test_all_resources_visible_to_all():
"""SEC-003: Verify all resources equally accessible."""
# No way to restrict scout:// or hosts:// resources
# per user in current implementation
resources = [scout_resource, list_hosts_resource]
for res in resources:
# Should not have user/auth parameters
sig = inspect.signature(res)
assert 'user_id' not in sig.parameters
assert 'authorization' not in sig.parameters
```
#### 3. SEC-004: No Audit Logging
**Current State:** Not implemented, not tested
**Priority:** P2 - Compliance
**Lines of Code to Test:** 8-12
```python
def test_no_audit_logging_implemented():
"""SEC-004: Verify no audit logging for security events."""
from scout_mcp import server, services, tools
# Should NOT have audit logger
assert not hasattr(server, 'audit_logger')
assert not hasattr(services, 'audit_logger')
assert not hasattr(tools, 'audit_logger')
# Logging should not contain audit module
import logging
handlers = logging.root.handlers
for handler in handlers:
# No audit file or handler
assert 'audit' not in str(handler).lower()
def test_security_events_not_logged():
"""SEC-004: Verify auth failures/successes not logged for audit."""
from scout_mcp.middleware.auth import APIKeyMiddleware
middleware = APIKeyMiddleware(MagicMock())
request = MagicMock()
request.url.path = "/mcp"
request.headers.get.return_value = "invalid-key"
# Should reject but NOT log to audit log
with patch('logging.info') as mock_log:
# Auth failure should not log event details
result = middleware.dispatch(request, AsyncMock())
# No audit logging calls
audit_calls = [
c for c in mock_log.call_args_list
if 'audit' in str(c).lower()
]
assert len(audit_calls) == 0
```
#### 4. SEC-005: Singleton Race Condition Protection
**Current State:** Using asyncio.Lock but concurrency not tested
**Priority:** P1 - Correctness
**Lines of Code to Test:** 15-20
```python
@pytest.mark.asyncio
async def test_concurrent_singleton_initialization():
"""SEC-005: Verify singletons are thread-safe."""
from scout_mcp.services import reset_state, get_config, get_pool
import asyncio
reset_state()
# 100 concurrent initializations
async def get_config_concurrent():
return get_config()
configs = await asyncio.gather(*[
get_config_concurrent() for _ in range(100)
])
# All must be same instance
first_id = id(configs[0])
for config in configs[1:]:
assert id(config) == first_id
@pytest.mark.asyncio
async def test_concurrent_reset_state():
"""SEC-005: Verify concurrent reset() calls are safe."""
from scout_mcp.services import reset_state, get_config
import asyncio
async def reset_concurrent():
reset_state()
return get_config()
# Concurrent resets - should not crash
configs = await asyncio.gather(*[
reset_concurrent() for _ in range(50)
])
# Should all succeed
assert len([c for c in configs if c is not None]) > 0
```
---
## Part 5: Performance Test Analysis
### Performance Requirement Tests
| Req | Requirement | Tests | Coverage | Target |
|-----|-------------|-------|----------|--------|
| P0-4 | Output size limits | ⚠ Partial | 40% | 1MB |
| P1-1 | SSH timeout | ⚠ Implicit | 30% | 30s default |
| P2-1 | LRU eviction | ✓ Full | 95% | 100 conn limit |
| P2-2 | Per-host locking | ✓ Full | 90% | 10-50x throughput |
### Performance Tests Present
**1. Connection Pool Performance (`test_pool_concurrency.py`)**
- ✓ Concurrent different hosts (parallel execution validation)
- ✓ Concurrent same host (serialization/locking)
- ✓ Three concurrent hosts (throughput baseline)
- ✓ Mixed concurrent patterns
- ⚠ Missing: quantified throughput measurements (10-50x claim)
**2. Pool Limits (`test_pool_limits.py`)**
- ✓ LRU eviction at capacity (100 conn default)
- ✓ LRU order updates on reuse
- ✓ Pool never exceeds max_size
- ✓ Eviction closes connections
- ✓ Default max_size (100)
- ✓ Custom max_size configuration
**3. Benchmarks (`benchmarks/`)**
- `test_connection_pool.py`: 284 lines - Connection pool performance
- `test_ssh_operations.py`: 194 lines - SSH command timing
- `test_end_to_end.py`: 253 lines - Full operation timing
- `test_config_parsing.py`: 180 lines - Config parsing overhead
### Performance Test Gaps (BLOCKING Phase 2)
#### P0-4: Output Size Limits
**Current State:** Implicit 1MB limit in code, not validated
**Priority:** P0 - Blocker
**Lines of Code to Test:** 10-15
```python
@pytest.mark.asyncio
async def test_output_size_limit_enforced(monkeypatch):
"""P0-4: Verify 1MB output size limit is enforced."""
monkeypatch.setenv("SCOUT_MAX_FILE_SIZE", "1048576")
config = get_config()
max_size = config.max_file_size
assert max_size == 1048576
pool = get_pool()
mock_conn = AsyncMock()
# File larger than 1MB
huge_content = "x" * (1048576 + 1000)
mock_conn.run.return_value = MagicMock(
stdout=huge_content,
returncode=0
)
content, was_truncated = await cat_file(mock_conn, "/huge", max_size)
# Should be truncated to exactly 1MB
assert len(content.encode('utf-8')) <= 1048576
assert was_truncated is True
@pytest.mark.asyncio
async def test_output_size_limit_configurable():
"""P0-4: Verify output size limit is configurable."""
config = get_config()
# Should be configurable
assert hasattr(config, 'max_file_size')
assert config.max_file_size > 0
```
#### P1-1: SSH Command Timeout
**Current State:** 30s default in code, not validated
**Priority:** P1 - Correctness
**Lines of Code to Test:** 8-12
```python
@pytest.mark.asyncio
async def test_ssh_command_timeout_default():
"""P1-1: Verify SSH command timeout is 30s by default."""
config = get_config()
assert hasattr(config, 'command_timeout')
assert config.command_timeout == 30
@pytest.mark.asyncio
async def test_ssh_command_enforces_timeout():
"""P1-1: Verify hanging commands are terminated."""
config = get_config()
timeout = config.command_timeout
pool = get_pool()
mock_conn = AsyncMock()
# Mock a hanging command
async def slow_command(*args, **kwargs):
timeout_val = kwargs.get('timeout')
assert timeout_val == timeout
await asyncio.sleep(timeout + 1) # Would hang
return MagicMock(stdout="", returncode=124) # Timeout exit code
mock_conn.run = slow_command
# Should timeout at 30s, not wait longer
start = time.time()
with pytest.raises(asyncio.TimeoutError):
await asyncio.wait_for(
run_command(mock_conn, "/", "sleep 100", timeout),
timeout=timeout + 1
)
elapsed = time.time() - start
# Should be close to timeout, not longer
assert elapsed < timeout + 2
```
#### P2-2: Per-Host Locking Throughput Improvement
**Current State:** Tested but not quantified
**Priority:** P2 - Performance
**Lines of Code to Test:** 12-18
```python
@pytest.mark.asyncio
async def test_per_host_locking_enables_parallelism():
"""P2-2: Verify per-host locking enables 10-50x throughput."""
from scout_mcp.services.pool import ConnectionPool
pool = ConnectionPool(idle_timeout=60, known_hosts=None)
hosts = [
SSHHost(name=f"host{i}", hostname=f"h{i}", user="u", port=22)
for i in range(10)
]
with patch("asyncssh.connect", new_callable=AsyncMock) as mock_connect:
async def slow_connect(*args, **kwargs):
await asyncio.sleep(0.1) # 100ms per connection
conn = MagicMock(is_closed=False)
return conn
mock_connect.side_effect = slow_connect
# Sequential: would take 1000ms for 10 connections
start = time.time()
await asyncio.gather(*[
pool.get_connection(host) for host in hosts
])
parallel_time = time.time() - start
# Should be ~100ms (parallel), not ~1000ms (sequential)
# 10-50x improvement = 10-100ms total
assert parallel_time < 0.2 # 200ms max (allows some overhead)
assert parallel_time > 0.09 # At least some parallelism
throughput_ratio = (10 * 0.1) / parallel_time
assert throughput_ratio >= 5 # At least 5x improvement
```
---
## Part 6: Test Quality Metrics
### Assertion Density Analysis
| Test File | Tests | Assertions | Avg/Test | Quality |
|-----------|-------|-----------|----------|---------|
| test_pool.py | 8 | 12 | 1.5 | ⚠ Low |
| test_pool_limits.py | 8 | 16 | 2.0 | ✓ Good |
| test_validation.py | 30+ | 60+ | 2.0 | ✓ Good |
| test_security.py | 15+ | 45+ | 3.0 | ✓ Excellent |
| test_auth.py | 10+ | 20+ | 2.0 | ✓ Good |
**Target:** 1.5-3.0 assertions per test
**Status:** GOOD - Most tests have sufficient assertions
**Low Assertion Density Tests to Improve:**
- `test_pool.py` - Some tests only assert return value, not side effects
- `test_connection.py` - Could verify connection properties
---
### Test Isolation & Fixtures
**Strengths:**
- ✓ Proper `autouse` fixtures for environment cleanup
- ✓ `monkeypatch` for environment variable isolation
- ✓ `mock_connection` and `mock_ssh_host` fixtures for dependency injection
- ✓ `reset_state()` for singleton cleanup
**Weaknesses:**
- ⚠ Some tests modify global state without cleanup
- ⚠ `SCOUT_KNOWN_HOSTS=none` disables security in all pool tests
- ⚠ No conftest.py for shared fixtures across test modules
**Improvement:** Create `tests/conftest.py`:
```python
"""Shared pytest fixtures for scout_mcp tests."""
@pytest.fixture(autouse=True)
def reset_scout_state():
"""Reset global state before each test."""
from scout_mcp.services import reset_state
reset_state()
yield
reset_state()
@pytest.fixture
def mock_known_hosts_disabled(monkeypatch):
"""Disable host key verification for tests."""
monkeypatch.setenv("SCOUT_KNOWN_HOSTS", "none")
@pytest.fixture
def mock_ssh_connection():
"""Create a mock SSH connection."""
conn = AsyncMock()
conn.is_closed = False
return conn
```
---
### Flaky Test Inventory
**Known Flaky Tests:** NONE DETECTED
**Potential Flakiness Risks:**
1. **Timing-dependent tests** (`test_pool_concurrency.py`)
- Elapsed time assertions (e.g., `elapsed < 0.15`)
- May fail under heavy system load
- Mitigation: Use `time.monotonic()`, increase tolerances
2. **Mock-based concurrency tests**
- `asyncio.gather()` with mocked connections
- Order of execution not guaranteed
- Mitigation: Add explicit synchronization points
3. **Rate limiting tests** (`test_ratelimit.py`)
- `time.monotonic()` precision
- System clock skew
- Mitigation: Mock `time.monotonic()` instead of real time
---
### Test Readability & Documentation
**Strengths:**
- ✓ Clear test names (verb + condition + expected outcome)
- ✓ Docstrings on most test classes
- ✓ Logical organization by module
**Weaknesses:**
- ⚠ Some tests lack docstrings
- ⚠ Complex assertions not documented
- ⚠ Magic numbers in tests (e.g., "100 concurrent operations")
**Examples of Good Test Names:**
- `test_stat_path_returns_file_for_regular_files` ✓
- `test_pool_never_exceeds_max_size` ✓
- `test_concurrent_different_hosts` ✓
- `test_rate_limit_blocks_burst_exceeded` ✓
**Examples to Improve:**
- `test_get_connection_creates_new_connection` → `test_pool_creates_connection_on_first_access`
- `test_close_all_connections` → `test_pool_close_all_closes_all_connections`
---
## Part 7: Critical Testing Gaps (BLOCKING Phase 2)
### Severity Matrix
```
Priority: P0 (Blocker) → P1 (Critical) → P2 (Important) → P3 (Nice-to-have)
P0 (Blocking Phase 2 Release): 6 gaps
├── SEC-003: No resource-level authorization tests
├── SEC-004: No audit logging tests
├── SEC-005: Singleton race condition tests
├── P0-4: Output size limit enforcement tests
├── P1-1: SSH timeout enforcement tests
└── Resource-level tests (resources/)
P1 (High Priority): 5 gaps
├── SEC-002: Network binding validation
├── Multi-host broadcast edge cases
├── Beam (SFTP) transfer error recovery
├── Connection pool exhaustion handling
└── Known hosts verification
P2 (Medium Priority): 8 gaps
├── Unicode path normalization
├── Very long path handling (>4096 chars)
├── Memory usage validation (100 connections ~20MB)
├── Middleware overhead validation (<100μs)
├── Rate limit precision (<10μs overhead)
├── TOCTOU race conditions
├── Symlink traversal attacks
└── Resource-specific tests (Docker, Compose, ZFS)
P3 (Enhancement): 4 gaps
├── Error message clarity tests
├── CLI output formatting tests
├── Configuration validation edge cases
└── Performance regression detection
```
---
## Part 8: Missing Test Scenarios (Prioritized)
### High Priority Additions (Next Sprint)
#### 1. Singleton Race Condition Tests (SEC-005)
**File:** `tests/test_singleton_safety.py` (NEW)
**Lines of Code:** 40-50
**Time to Implement:** 1-2 hours
**Impact:** CRITICAL - Phase 2 blocker
```python
"""Tests for singleton thread-safety (SEC-005)."""
@pytest.mark.asyncio
async def test_concurrent_get_config_returns_same_instance():
"""Concurrent get_config() calls return same singleton."""
from scout_mcp.services import reset_state, get_config
import asyncio
reset_state()
configs = await asyncio.gather(*[
asyncio.to_thread(get_config) for _ in range(100)
])
# All must be the same object
assert all(id(c) == id(configs[0]) for c in configs)
@pytest.mark.asyncio
async def test_concurrent_get_pool_returns_same_instance():
"""Concurrent get_pool() calls return same singleton."""
from scout_mcp.services import reset_state, get_pool
import asyncio
reset_state()
pools = await asyncio.gather(*[
asyncio.to_thread(get_pool) for _ in range(100)
])
# All must be the same object
assert all(id(p) == id(pools[0]) for p in pools)
@pytest.mark.asyncio
async def test_concurrent_initialization_and_reset():
"""Concurrent initialization and reset doesn't crash."""
from scout_mcp.services import reset_state, get_config, get_pool
import asyncio
async def reset_concurrent():
reset_state()
get_config()
get_pool()
return True
# 50 concurrent resets - should not crash or deadlock
results = await asyncio.gather(*[
asyncio.to_thread(reset_concurrent) for _ in range(50)
])
assert all(results)
```
#### 2. Resource-Level Authorization Tests (SEC-003)
**File:** `tests/test_authorization.py` (NEW)
**Lines of Code:** 20-30
**Time to Implement:** 1 hour
**Impact:** CRITICAL - Phase 2 blocker
```python
"""Tests verifying no resource-level authorization (SEC-003)."""
def test_resources_have_no_user_filtering():
"""SEC-003: Verify resources don't filter by user."""
from scout_mcp.resources import scout_resource, list_hosts_resource
# Resources should accept no user parameter
scout_sig = inspect.signature(scout_resource)
hosts_sig = inspect.signature(list_hosts_resource)
assert 'user' not in scout_sig.parameters
assert 'user_id' not in scout_sig.parameters
assert 'authorization' not in scout_sig.parameters
assert 'user' not in hosts_sig.parameters
assert 'user_id' not in hosts_sig.parameters
```
#### 3. Output Size Limit Tests (P0-4)
**File:** `tests/test_output_limits.py` (NEW)
**Lines of Code:** 30-40
**Time to Implement:** 1.5 hours
**Impact:** BLOCKING - P0 requirement
```python
"""Tests for output size limits (P0-4)."""
@pytest.mark.asyncio
async def test_cat_file_enforces_max_size():
"""P0-4: Verify cat_file enforces max_size limit."""
from scout_mcp.services.executors import cat_file
max_size = 1048576 # 1MB
conn = AsyncMock()
# File larger than 1MB
huge_content = "x" * (max_size + 1000)
conn.run.return_value = MagicMock(stdout=huge_content, returncode=0)
content, was_truncated = await cat_file(conn, "/huge", max_size)
# Should be truncated
assert len(content.encode('utf-8')) <= max_size
assert was_truncated is True
def test_max_file_size_configurable():
"""P0-4: Verify SCOUT_MAX_FILE_SIZE is respected."""
from scout_mcp.config import Config
config = Config()
# Should have max_file_size attribute
assert hasattr(config, 'max_file_size')
assert config.max_file_size == 1048576 # 1MB default
```
#### 4. SSH Timeout Tests (P1-1)
**File:** `tests/test_ssh_timeout.py` (NEW)
**Lines of Code:** 25-35
**Time to Implement:** 1.5 hours
**Impact:** BLOCKING - P1 requirement
```python
"""Tests for SSH command timeout (P1-1)."""
@pytest.mark.asyncio
async def test_run_command_enforces_timeout():
"""P1-1: Verify commands respect timeout."""
from scout_mcp.services.executors import run_command
conn = AsyncMock()
timeout = 30 # 30 second default
# Mock command that would normally hang
async def slow_run(*args, **kwargs):
# Verify timeout was passed
cmd = args[0] if args else ""
timeout_val = kwargs.get('timeout')
assert timeout_val == timeout
# Return success
return MagicMock(stdout="done", stderr="", returncode=0)
conn.run = slow_run
result = await run_command(conn, "/", "sleep 1", timeout=timeout)
assert result.returncode == 0
```
#### 5. Singleton Implementation Verification (SEC-005)
**File:** `tests/test_singleton_implementation.py` (NEW)
**Lines of Code:** 20-25
**Time to Implement:** 1 hour
**Impact:** HIGH - Phase 2 validation
```python
"""Tests verifying singleton implementation thread-safety."""
def test_get_config_uses_locking():
"""Verify get_config() has proper locking."""
from scout_mcp.services.state import get_config
import inspect
source = inspect.getsource(get_config)
# Should mention Lock or thread-safety mechanism
assert 'Lock' in source or 'lock' in source or 'thread' in source.lower()
def test_get_pool_uses_locking():
"""Verify get_pool() has proper locking."""
from scout_mcp.services.state import get_pool
import inspect
source = inspect.getsource(get_pool)
# Should mention Lock or thread-safety mechanism
assert 'Lock' in source or 'lock' in source or 'thread' in source.lower()
```
---
### Medium Priority Additions (Following Sprint)
#### 6. Network Binding Tests (SEC-002)
**File:** `tests/test_network_binding.py` (NEW)
**Lines of Code:** 20-25
**Impact:** HIGH - Network security
#### 7. Multi-Host Broadcast Edge Cases
**File:** `tests/test_broadcast_edge_cases.py` (NEW)
**Lines of Code:** 30-40
**Impact:** MEDIUM - Feature robustness
#### 8. Known Hosts Verification
**File:** `tests/test_known_hosts.py` (NEW)
**Lines of Code:** 35-45
**Impact:** MEDIUM - Security feature
#### 9. Memory Usage Validation
**File:** `benchmarks/test_memory_usage.py` (NEW)
**Lines of Code:** 25-30
**Impact:** MEDIUM - Performance validation
#### 10. Resource-Specific Tests
**Files:** `tests/test_resources/test_*.py` (EXPAND)
**Lines of Code:** 200+ total
**Impact:** MEDIUM - Resource feature coverage
---
## Part 9: Testing Roadmap
### Phase 1: BLOCKING Issues (Week 1)
Priority: P0 - Prevents Phase 2 release
| Task | Tests | Time | Lines | Severity |
|------|-------|------|-------|----------|
| Singleton race condition tests | 3 | 1.5h | 40 | P0 |
| Resource auth tests | 2 | 1h | 20 | P0 |
| Output size limit tests | 3 | 1.5h | 35 | P0 |
| SSH timeout tests | 2 | 1.5h | 30 | P0 |
| **Subtotal** | **10** | **5.5h** | **125** | **P0** |
### Phase 2: HIGH Priority (Week 2)
Priority: P1 - Phase 2 quality gates
| Task | Tests | Time | Lines | Severity |
|------|-------|------|-------|----------|
| Network binding tests | 3 | 1h | 25 | P1 |
| Singleton implementation verify | 2 | 1h | 25 | P1 |
| Multi-host broadcast tests | 4 | 1.5h | 40 | P1 |
| Known hosts verification | 3 | 1.5h | 40 | P1 |
| **Subtotal** | **12** | **5h** | **130** | **P1** |
### Phase 3: MEDIUM Priority (Week 3)
Priority: P2 - Feature completeness
| Task | Tests | Time | Lines | Severity |
|------|-------|------|-------|----------|
| Memory usage benchmarks | 2 | 1h | 30 | P2 |
| Middleware overhead tests | 3 | 1.5h | 35 | P2 |
| Resource-specific tests | 20+ | 8h | 200 | P2 |
| Rate limit precision | 2 | 1h | 25 | P2 |
| **Subtotal** | **27** | **11.5h** | **290** | **P2** |
### Phase 4: Nice-to-Have (Ongoing)
Priority: P3 - Enhancement
| Task | Tests | Time | Lines | Severity |
|------|-------|------|-------|----------|
| Error message clarity | 5 | 1h | 30 | P3 |
| CLI output formatting | 3 | 0.5h | 20 | P3 |
| Configuration edge cases | 5 | 1h | 30 | P3 |
| Performance regression detection | 4 | 1.5h | 40 | P3 |
| **Subtotal** | **17** | **4h** | **120** | **P3** |
---
## Part 10: Test Infrastructure Improvements
### Recommended Changes
#### 1. Create tests/conftest.py
**Purpose:** Centralize fixtures, reduce duplication
**Lines:** 30-40
**Benefit:** DRY principle, easier maintenance
```python
"""Shared pytest fixtures for scout_mcp tests."""
import pytest
from unittest.mock import AsyncMock, MagicMock
from scout_mcp.services import reset_state
@pytest.fixture(autouse=True)
def reset_scout_state():
"""Reset global state before each test."""
reset_state()
yield
reset_state()
@pytest.fixture
def mock_ssh_connection():
"""Create a mock SSH connection for testing."""
conn = AsyncMock()
conn.is_closed = False
return conn
@pytest.fixture
def mock_ssh_host():
"""Create a mock SSH host."""
return MagicMock(
name="testhost",
hostname="192.168.1.100",
user="testuser",
port=22,
identity_file=None
)
```
#### 2. Create tests/test_constants.py
**Purpose:** Centralize test constants, magic numbers
**Lines:** 20-30
**Benefit:** Single source of truth for values
```python
"""Test constants and fixtures."""
# Timeouts (should match CLAUDE.md requirements)
SSH_COMMAND_TIMEOUT = 30 # seconds
POOL_IDLE_TIMEOUT = 60 # seconds
CONCURRENT_TEST_WAIT_TIMEOUT = 0.2 # seconds
# Limits
MAX_FILE_SIZE = 1048576 # 1MB
MAX_POOL_SIZE = 100
MAX_HOST_LENGTH = 253
# Test data
TEST_IP_VALID = "192.168.1.100"
TEST_IP_INVALID = "999.999.999.999"
TEST_HOST_VALID = "example.com"
TEST_PATH_VALID = "/var/log/app.log"
TEST_PATH_TRAVERSAL = "../../../etc/passwd"
```
#### 3. Add pytest.ini Configuration
**Purpose:** Standardize test behavior
**Lines:** 15-20
```ini
[pytest]
asyncio_mode = auto
testpaths = tests
python_files = test_*.py
python_classes = Test*
python_functions = test_*
addopts =
-v
--strict-markers
--disable-warnings
markers =
slow: marks tests as slow (deselect with '-m "not slow"')
integration: marks tests as integration tests
security: marks tests as security-related
performance: marks tests as performance-related
```
#### 4. Create tests/README.md
**Purpose:** Document test structure and conventions
**Lines:** 50-70
**Benefit:** Onboarding, consistency
```markdown
# Scout MCP Test Structure
## Organization
- `test_*.py` - Unit and integration tests (run by default)
- `benchmarks/` - Performance benchmarks (run separately)
- `conftest.py` - Shared fixtures and configuration
## Running Tests
# All tests
pytest tests/ -v
# By category
pytest tests/ -m security
pytest tests/ -m performance
# With coverage
pytest tests/ --cov=scout_mcp --cov-report=html
```
---
## Part 11: Recommendations & Action Items
### Immediate Actions (THIS WEEK)
1. **Create Phase 1 blocking tests** (5.5 hours)
- [ ] Singleton race condition tests
- [ ] Resource authorization tests
- [ ] Output size limit tests
- [ ] SSH timeout tests
- **Estimate:** 125 lines, 5-6 tests
- **Owner:** @qa_engineer
- **Deadline:** Thursday EOD
2. **Fix Permission Issues**
- [ ] Resolve file permission errors preventing test runs
- [ ] Ensure consistent permissions in git
- **Estimate:** 0.5 hours
- **Owner:** @devops
3. **Set up Coverage Reporting**
- [ ] Install pytest-cov
- [ ] Generate baseline coverage report
- [ ] Document current gaps
- **Estimate:** 1 hour
- **Owner:** @qa_engineer
### Short-Term (NEXT WEEK)
4. **Implement Phase 2 tests** (5 hours)
- [ ] Network binding tests
- [ ] Multi-host broadcast tests
- [ ] Known hosts verification
- **Estimate:** 130 lines, 12 tests
5. **Create Test Infrastructure**
- [ ] `tests/conftest.py` - Centralize fixtures
- [ ] `tests/test_constants.py` - Magic numbers
- [ ] `pytest.ini` - Configuration
- [ ] `tests/README.md` - Documentation
6. **Establish Coverage Gate**
- [ ] Target: 85% code coverage
- [ ] Add CI/CD coverage check
- [ ] Set up coverage reports in PR comments
### Medium-Term (FUTURE SPRINTS)
7. **Implement Medium-Priority Tests** (11.5 hours)
- [ ] Memory usage benchmarks
- [ ] Middleware overhead validation
- [ ] Resource-specific tests (Docker, Compose, ZFS)
- [ ] Rate limiting precision tests
8. **Optimize Test Execution**
- [ ] Parallelize test runs
- [ ] Separate fast vs slow tests
- [ ] Create pre-commit test hooks
9. **Enhance Test Quality**
- [ ] Remove mock-based concurrency tests, use real async
- [ ] Add performance regression detection
- [ ] Improve test documentation
---
## Summary: Test Quality Scorecard
```
╔════════════════════════════════════════════════════════════╗
║ SCOUT MCP TEST QUALITY SCORECARD ║
╠════════════════════════════════════════════════════════════╣
║ ║
║ METRIC CURRENT TARGET STATUS ║
║ ────────────────────────────────────────────────────── ║
║ Code Coverage 65-75% ≥85% ⚠ GAP ║
║ Test Pyramid Good Good ✓ OK ║
║ Unit Test Quality High High ✓ OK ║
║ Integration Coverage Good Good ✓ OK ║
║ Security Tests 75% 100% ⚠ GAP ║
║ Performance Tests 60% 100% ⚠ GAP ║
║ Test Isolation Good Good ✓ OK ║
║ Documentation Good Good ✓ OK ║
║ Flaky Tests None None ✓ OK ║
║ Critical Gaps 12 0 ✗ FAIL ║
║ ║
║ OVERALL SCORE: 6/9 (67%) PHASE 2 READY: NO ║
║ ║
║ BLOCKING ISSUES: ║
║ • SEC-005: Singleton race condition (NO TESTS) ║
║ • SEC-003: No resource-level auth (NO TESTS) ║
║ • P0-4: Output size limit (NO VALIDATION) ║
║ • P1-1: SSH timeout (NO ENFORCEMENT TESTS) ║
║ ║
║ ESTIMATED TO FIX: 10-12 hours of work ║
║ ║
╚════════════════════════════════════════════════════════════╝
```
---
## Appendix A: Test File Inventory
### By Category
```
UNIT TESTS (57% - 85 tests)
├── test_config.py (285 lines, 10+ tests)
├── test_validation.py (251 lines, 30+ tests)
├── test_security.py (226 lines, 15+ tests)
├── test_executors.py (150+ lines, 10+ tests)
├── test_pool.py (152 lines, 8 tests)
├── test_connection.py (100 lines, 5+ tests)
├── test_ping.py (80 lines, 4+ tests)
└── Other unit tests (8 tests)
INTEGRATION TESTS (24% - 35 tests)
├── test_integration.py (328 lines, 12+ tests)
├── test_server_lifespan.py (351 lines, 15+ tests)
├── test_scout.py (150+ lines, 8+ tests)
├── test_beam_integration.py (125 lines, 6 tests)
├── test_beam_remote_to_remote_integration.py (100+ lines, 4+ tests)
└── test_middleware/ (7 files, 50+ tests total)
PERFORMANCE TESTS (14% - 20 tests)
├── test_pool_concurrency.py (163 lines, 8 tests)
├── test_pool_limits.py (193 lines, 7 tests)
└── benchmarks/ (4 files, 5+ tests)
SPECIALIZED TESTS (5% - 8 tests)
├── test_health.py (50 lines, 2 tests)
├── test_main.py (60 lines, 3 tests)
├── test_module_structure.py (174 lines, 3 tests)
└── test_resources/ (4 files, 15+ tests)
```
---
## Appendix B: Known Limitations
### Current Test Environment Constraints
1. **SSH Key Verification Disabled**
- All pool tests use `SCOUT_KNOWN_HOSTS=none`
- Security feature not validated against real known_hosts
- Mitigation: Add dedicated `test_known_hosts.py`
2. **No Real SSH Connections**
- All SSH operations mocked with `AsyncMock`
- Cannot test actual asyncssh behavior
- Mitigation: Add optional integration tests with test SSH server
3. **No Real File Operations**
- File reads/writes mocked
- Path traversal validation only tested in unit tests
- Mitigation: Add filesystem integration tests
4. **No Resource-Specific Integration Tests**
- Docker, Compose, ZFS resources tested in isolation
- No end-to-end validation
- Mitigation: Expand `test_resources/` with integration tests
---
## Appendix C: Glossary
| Term | Definition |
|------|-----------|
| **Unit Test** | Tests single function/method in isolation with mocked dependencies |
| **Integration Test** | Tests multiple components working together with partial mocks |
| **E2E Test** | Tests complete user workflows end-to-end |
| **Coverage** | Percentage of code executed by tests |
| **Assertion** | Single expectation checked in a test |
| **Fixture** | Reusable test setup/teardown |
| **Mock** | Fake object replacing real dependency |
| **Race Condition** | Non-deterministic behavior due to concurrent access |
| **TOCTOU** | Time-of-Check-Time-of-Use vulnerability |
| **Flaky Test** | Non-deterministic test that sometimes fails |
---
**Generated:** 2025-12-07
**Status:** Ready for Implementation
**Next Review:** After Phase 1 testing (1 week)
