xsecuremcp / tests /policy /test_policy_engine.py
svkrishna
Phase 1 : Pluggable Policy Engine — design an interface that allows policies to be loaded/unloaded at runtime; each policy should define machine-checkable invariants and decision logic.
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"""Tests for the policy engine."""
import pytest
from pathlib import Path
from unittest.mock import Mock, patch
from fastmcp.policy import PolicyEngine, PolicyRegistry, Decision
from fastmcp.policy.policies import MinimumNecessaryAccessPolicy, RBACPolicy
class TestPolicyEngine:
"""Test the policy engine functionality."""
@pytest.fixture
def policy_engine(self):
"""Create a policy engine for testing."""
return PolicyEngine()
@pytest.fixture
def sample_context(self):
"""Create a sample context for testing."""
return {
"user": {
"id": "user123",
"roles": ["user"],
"permissions": ["read", "write"]
},
"action": "read",
"resource": {
"type": "document",
"id": "doc123",
"owner": "user123",
"visibility": "private"
}
}
def test_policy_engine_initialization(self, policy_engine):
"""Test policy engine initialization."""
assert policy_engine.registry is not None
assert isinstance(policy_engine.registry, PolicyRegistry)
assert policy_engine._evaluation_order == []
def test_set_evaluation_order(self, policy_engine):
"""Test setting evaluation order."""
order = ["policy1", "policy2", "policy3"]
policy_engine.set_evaluation_order(order)
assert policy_engine._evaluation_order == order
@pytest.mark.asyncio
async def test_evaluate_no_policies(self, policy_engine, sample_context):
"""Test evaluation when no policies are registered."""
decision = await policy_engine.evaluate(sample_context)
assert decision.allow is True
assert "All policies evaluated successfully" in decision.reason
@pytest.mark.asyncio
async def test_evaluate_single_policy(self, policy_engine, sample_context):
"""Test evaluation of a single policy."""
# Register a policy
policy = MinimumNecessaryAccessPolicy()
policy_engine.register_policy(policy)
# Evaluate
decision = await policy_engine.evaluate(sample_context)
assert decision.allow is True
# The policy engine returns its own response, not the individual policy response
assert "All policies evaluated successfully" in decision.reason
@pytest.mark.asyncio
async def test_evaluate_specific_policies(self, policy_engine, sample_context):
"""Test evaluation of specific policies."""
# Register multiple policies
policy1 = MinimumNecessaryAccessPolicy(name="policy1")
policy2 = RBACPolicy(name="policy2")
policy_engine.register_policy(policy1)
policy_engine.register_policy(policy2)
# Evaluate only policy1
decision = await policy_engine.evaluate(sample_context, ["policy1"])
assert decision.allow is True
@pytest.mark.asyncio
async def test_evaluate_policy_denial(self, policy_engine):
"""Test evaluation when a policy denies access."""
# Create context with sensitive action
context = {
"user": {"roles": ["user"]},
"action": "delete",
"resource": {"type": "user_data"}
}
# Register minimum necessary policy
policy = MinimumNecessaryAccessPolicy()
policy_engine.register_policy(policy)
# Evaluate
decision = await policy_engine.evaluate(context)
assert decision.allow is False
assert "requires justification" in decision.reason
@pytest.mark.asyncio
async def test_evaluate_single_policy_method(self, policy_engine, sample_context):
"""Test evaluate_single_policy method."""
# Register a policy
policy = MinimumNecessaryAccessPolicy(name="test_policy")
policy_engine.register_policy(policy)
# Evaluate single policy
decision = await policy_engine.evaluate_single_policy("test_policy", sample_context)
assert decision is not None
assert decision.allow is True
@pytest.mark.asyncio
async def test_evaluate_single_policy_not_found(self, policy_engine, sample_context):
"""Test evaluate_single_policy with non-existent policy."""
decision = await policy_engine.evaluate_single_policy("non_existent", sample_context)
assert decision is None
def test_get_policy_metadata(self, policy_engine):
"""Test getting policy metadata."""
# Register policies
policy1 = MinimumNecessaryAccessPolicy(name="policy1")
policy2 = RBACPolicy(name="policy2")
policy_engine.register_policy(policy1)
policy_engine.register_policy(policy2)
metadata = policy_engine.get_policy_metadata()
assert len(metadata) == 2
assert any(p["name"] == "policy1" for p in metadata)
assert any(p["name"] == "policy2" for p in metadata)
def test_register_unregister_policy(self, policy_engine):
"""Test policy registration and unregistration."""
policy = MinimumNecessaryAccessPolicy(name="test_policy")
# Register
policy_engine.register_policy(policy)
assert policy_engine.registry.get_policy("test_policy") is not None
# Unregister
unregistered = policy_engine.unregister_policy("test_policy")
assert unregistered is not None
assert unregistered.name == "test_policy"
assert policy_engine.registry.get_policy("test_policy") is None
class TestPolicyRegistry:
"""Test the policy registry functionality."""
@pytest.fixture
def registry(self):
"""Create a policy registry for testing."""
return PolicyRegistry()
def test_registry_initialization(self, registry):
"""Test registry initialization."""
assert registry._policies == {}
assert registry._policy_classes == {}
def test_register_policy(self, registry):
"""Test policy registration."""
policy = MinimumNecessaryAccessPolicy()
registry.register_policy(policy)
assert "minimum_necessary_access" in registry._policies
def test_unregister_policy(self, registry):
"""Test policy unregistration."""
policy = MinimumNecessaryAccessPolicy()
registry.register_policy(policy)
unregistered = registry.unregister_policy("minimum_necessary_access")
assert unregistered is not None
assert "minimum_necessary_access" not in registry._policies
def test_get_policy(self, registry):
"""Test getting a policy."""
policy = MinimumNecessaryAccessPolicy()
registry.register_policy(policy)
retrieved = registry.get_policy("minimum_necessary_access")
assert retrieved is not None
assert retrieved.name == "minimum_necessary_access"
def test_list_policies(self, registry):
"""Test listing policies."""
policy1 = MinimumNecessaryAccessPolicy(name="policy1")
policy2 = RBACPolicy(name="policy2")
registry.register_policy(policy1)
registry.register_policy(policy2)
policies = registry.list_policies()
assert len(policies) == 2
assert any(p["name"] == "policy1" for p in policies)
assert any(p["name"] == "policy2" for p in policies)
def test_register_policy_class(self, registry):
"""Test registering a policy class."""
registry.register_policy_class("test_policy", MinimumNecessaryAccessPolicy)
assert "test_policy" in registry._policy_classes
assert registry._policy_classes["test_policy"] == MinimumNecessaryAccessPolicy
def test_register_invalid_policy_class(self, registry):
"""Test registering an invalid policy class."""
with pytest.raises(ValueError):
registry.register_policy_class("invalid", str)
def test_create_policy_from_config(self, registry):
"""Test creating policy from configuration."""
registry.register_policy_class("test_policy", MinimumNecessaryAccessPolicy)
config = {
"type": "test_policy",
"parameters": {
"name": "config_policy",
"required_justification": False
}
}
policy = registry.create_policy_from_config(config)
assert policy is not None
assert policy.name == "config_policy"
assert isinstance(policy, MinimumNecessaryAccessPolicy)
def test_create_policy_from_invalid_config(self, registry):
"""Test creating policy from invalid configuration."""
config = {"type": "non_existent"}
policy = registry.create_policy_from_config(config)
assert policy is None
class TestPolicyLoadAndReload:
"""Test policy loading and hot-reload functionality."""
@pytest.fixture
def registry(self):
"""Create a policy registry for testing."""
return PolicyRegistry()
@pytest.fixture
def yaml_config_file(self, tmp_path):
"""Create a temporary YAML config file."""
config_content = """
policies:
- name: yaml_policy1
type: minimum_necessary
parameters:
required_justification: false
- name: yaml_policy2
type: rbac
parameters:
version: "1.0.0"
"""
config_file = tmp_path / "policies.yaml"
config_file.write_text(config_content)
return config_file
def test_load_policies_from_yaml(self, registry, yaml_config_file):
"""Test loading policies from YAML file."""
# Register policy classes
registry.register_policy_class("minimum_necessary", MinimumNecessaryAccessPolicy)
registry.register_policy_class("rbac", RBACPolicy)
# Load from YAML
registry.load_policies_from_yaml(yaml_config_file)
# Check that policies were loaded
assert registry.get_policy("yaml_policy1") is not None
assert registry.get_policy("yaml_policy2") is not None
def test_hot_reload_policies(self, registry, yaml_config_file):
"""Test hot reloading policies."""
# Register policy classes
registry.register_policy_class("minimum_necessary", MinimumNecessaryAccessPolicy)
registry.register_policy_class("rbac", RBACPolicy)
# Initial load
registry.load_policies_from_yaml(yaml_config_file)
initial_count = len(registry._policies)
# Hot reload
registry.hot_reload_policies(yaml_config_file)
# Check that policies were reloaded
assert len(registry._policies) == initial_count
assert registry.get_policy("yaml_policy1") is not None
assert registry.get_policy("yaml_policy2") is not None
@patch('importlib.metadata.entry_points')
def test_load_policy_from_entry_point(self, mock_entry_points, registry):
"""Test loading policies from entry points."""
# Mock entry points
mock_entry_point = Mock()
mock_entry_point.name = "test_policy"
mock_entry_point.load.return_value = MinimumNecessaryAccessPolicy
mock_entry_points.return_value.select.return_value = [mock_entry_point]
# Load from entry points
registry.load_policy_from_entry_point("fastmcp.policies")
# Check that policy was loaded
assert registry.get_policy("test_policy") is not None
class TestPolicyIntegration:
"""Test policy integration with FastMCP server."""
@pytest.mark.asyncio
async def test_policy_engine_with_server(self):
"""Test policy engine integration with FastMCP server."""
from fastmcp import FastMCP
# Create server with policy engine
server = FastMCP("Test Server")
policy_engine = server.enable_policy_engine()
# Register policies
policy_engine.register_policy(MinimumNecessaryAccessPolicy())
policy_engine.register_policy(RBACPolicy())
# Test that policy engine is accessible
assert server.get_policy_engine() is not None
assert server.get_policy_engine() == policy_engine
# Test policy evaluation
context = {
"user": {"roles": ["user"]},
"action": "read",
"resource": {"type": "document"}
}
decision = await policy_engine.evaluate(context)
assert decision.allow is True