fastapi-gsap/tests/test_entra_driver.py

# Copyright 2026 Guildhouse Dev
# SPDX-License-Identifier: Apache-2.0

"""Tests for the Entra identity driver — C-3, H-10."""

import pytest
from unittest.mock import AsyncMock, patch
from jose import jwt as jose_jwt
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives import serialization
from gsap_broker.drivers.entra import EntraDriver
from gsap_broker.drivers.jwks import AuthenticationError


def _generate_rsa_keypair():
    private_key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
    public_key = private_key.public_key()
    return private_key, public_key


def _private_key_pem(private_key):
    return private_key.private_bytes(
        encoding=serialization.Encoding.PEM,
        format=serialization.PrivateFormat.PKCS8,
        encryption_algorithm=serialization.NoEncryption(),
    )


def _public_numbers_to_jwk(public_key, kid="test-kid-1"):
    import base64
    nums = public_key.public_numbers()
    e_bytes = nums.e.to_bytes((nums.e.bit_length() + 7) // 8, "big")
    n_bytes = nums.n.to_bytes((nums.n.bit_length() + 7) // 8, "big")
    return {
        "kty": "RSA",
        "kid": kid,
        "use": "sig",
        "alg": "RS256",
        "n": base64.urlsafe_b64encode(n_bytes).rstrip(b"=").decode(),
        "e": base64.urlsafe_b64encode(e_bytes).rstrip(b"=").decode(),
    }


PRIVATE_KEY, PUBLIC_KEY = _generate_rsa_keypair()
KID = "test-kid-1"
TENANT_ID = "test-tenant-id-1234"
CLIENT_ID = "test-client-id-5678"
JWKS = {"keys": [_public_numbers_to_jwk(PUBLIC_KEY, KID)]}


def _make_token(claims: dict, kid: str = KID, expired: bool = False) -> str:
    import datetime
    now = datetime.datetime.now(datetime.UTC)
    base_claims = {
        "iss": f"https://login.microsoftonline.com/{TENANT_ID}/v2.0",
        "aud": CLIENT_ID,
        "iat": int(now.timestamp()),
        "nbf": int(now.timestamp()),
        "exp": int((now + datetime.timedelta(hours=1)).timestamp()),
        "oid": "user-oid-1",
        "tid": TENANT_ID,
        "preferred_username": "alice@contoso.com",
        "name": "Alice Smith",
        "jti": "test-jti",
    }
    if expired:
        base_claims["exp"] = int((now - datetime.timedelta(hours=1)).timestamp())
        base_claims["nbf"] = int((now - datetime.timedelta(hours=2)).timestamp())
        base_claims["iat"] = int((now - datetime.timedelta(hours=2)).timestamp())
    base_claims.update(claims)
    return jose_jwt.encode(
        base_claims, _private_key_pem(PRIVATE_KEY), algorithm="RS256", headers={"kid": kid}
    )


def _driver_config(raw_token: str = "", extra: dict = None) -> dict:
    config = {
        "_raw_token": raw_token,
        "entra_tenant_id": TENANT_ID,
        "entra_client_id": CLIENT_ID,
        "domain": "contoso.com",
    }
    if extra:
        config.update(extra)
    return config


@pytest.fixture
def mock_jwks_fetch():
    """Mock the JWKS HTTP fetch to return test keys."""
    with patch("gsap_broker.drivers.jwks.httpx.AsyncClient") as mock_http:
        import unittest.mock
        mock_resp = unittest.mock.MagicMock()
        mock_resp.json.return_value = JWKS
        mock_resp.raise_for_status = unittest.mock.MagicMock()

        ctx_manager = AsyncMock()
        ctx_manager.__aenter__.return_value.get = AsyncMock(return_value=mock_resp)
        mock_http.return_value = ctx_manager
        yield mock_http


@pytest.mark.asyncio
async def test_authenticate_valid_token(mock_jwks_fetch):
    token = _make_token({"roles": ["admin"], "amr": ["pwd", "mfa"]})
    driver = EntraDriver(config=_driver_config(raw_token=token))
    result = await driver.authenticate()

    assert result.is_authorized
    assert result.principal_did == "did:web:contoso.com:principal:user-oid-1"
    assert result.mfa_satisfied is True


@pytest.mark.asyncio
async def test_authenticate_extracts_device_id(mock_jwks_fetch):
    token = _make_token({"deviceid": "device-abc-123"})
    driver = EntraDriver(config=_driver_config(raw_token=token))
    result = await driver.authenticate()
    assert result.device_id == "device-abc-123"


@pytest.mark.asyncio
async def test_authenticate_no_device_id(mock_jwks_fetch):
    token = _make_token({})
    driver = EntraDriver(config=_driver_config(raw_token=token))
    result = await driver.authenticate()
    assert result.device_id is None


@pytest.mark.asyncio
async def test_authenticate_expired_token(mock_jwks_fetch):
    token = _make_token({}, expired=True)
    driver = EntraDriver(config=_driver_config(raw_token=token))
    result = await driver.authenticate()
    assert not result.is_authorized


@pytest.mark.asyncio
async def test_authenticate_no_token():
    driver = EntraDriver(config={"_raw_token": "", "entra_tenant_id": TENANT_ID})
    result = await driver.authenticate()
    assert not result.is_authorized
    assert "No token" in result.denial_reason


@pytest.mark.asyncio
async def test_authenticate_mfa_detection(mock_jwks_fetch):
    token = _make_token({"amr": ["pwd", "mfa"]})
    driver = EntraDriver(config=_driver_config(raw_token=token))
    result = await driver.authenticate()
    assert result.mfa_satisfied is True

    token = _make_token({"amr": ["pwd"]})
    driver = EntraDriver(config=_driver_config(raw_token=token))
    result = await driver.authenticate()
    assert result.mfa_satisfied is False


@pytest.mark.asyncio
async def test_authenticate_elevation_required(mock_jwks_fetch):
    token = _make_token({"roles": ["reader"]})
    config = _driver_config(raw_token=token, extra={
        "requested_accord": "admin-ops",
        "accord_roles": {"admin-ops": "admin-role"},
    })
    driver = EntraDriver(config=config)
    result = await driver.authenticate()
    assert result.needs_elevation


@pytest.mark.asyncio
async def test_did_construction(mock_jwks_fetch):
    token = _make_token({"oid": "unique-user-oid"})
    driver = EntraDriver(config=_driver_config(raw_token=token, extra={"domain": "example.dev"}))
    result = await driver.authenticate()
    assert result.principal_did == "did:web:example.dev:principal:unique-user-oid"


@pytest.mark.asyncio
async def test_wrong_kid_rejected_then_refreshed(mock_jwks_fetch):
    """H-10: kid miss triggers JWKS refresh. With only one JWKS response,
    the second fetch still has the same keys, so unknown kid is rejected."""
    token = _make_token({}, kid="unknown-kid")
    driver = EntraDriver(config=_driver_config(raw_token=token))
    result = await driver.authenticate()
    assert not result.is_authorized
    assert "signing key" in result.denial_reason.lower() or "key" in result.denial_reason.lower()


@pytest.mark.asyncio
async def test_jwks_failure_denies_no_fallback():
    """C-3: JWKS fetch failure results in denial, no fallback."""
    with patch("gsap_broker.drivers.jwks.httpx.AsyncClient") as mock_http:
        ctx_manager = AsyncMock()
        ctx_manager.__aenter__.return_value.get = AsyncMock(
            side_effect=Exception("Network unreachable")
        )
        mock_http.return_value = ctx_manager

        token = _make_token({})
        driver = EntraDriver(config=_driver_config(raw_token=token))
        result = await driver.authenticate()

        assert not result.is_authorized
        assert "JWKS fetch failed" in result.denial_reason