feat(mcp): 5 outils todos + tests

Ajoute mcp_server.py avec get_todos, create_todo, update_todo, postpone_todo, delete_todo.
Ajoute test_mcp.py (7 tests). Corrige conftest pour injecter NullPool dans AsyncSessionLocal des outils MCP (évite les conflits d'event loop entre tests).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/tests/conftest.py

@@ -5,6 +5,7 @@ from sqlalchemy.pool import NullPool
 from app.main import app
 from app.core import database
 from app.core.config import settings
+import app.api.mcp_server as mcp_server_module
 
 
 def make_test_engine():
@@ -12,6 +13,19 @@ def make_test_engine():
     return create_async_engine(settings.database_url, poolclass=NullPool)
 
 
+@pytest.fixture(autouse=True)
+async def mcp_nullpool_session():
+    """Remplace AsyncSessionLocal dans mcp_server par un sessionmaker NullPool
+    pour éviter les conflits d'event loop entre tests."""
+    engine = make_test_engine()
+    test_session_factory = async_sessionmaker(engine, expire_on_commit=False)
+    original = mcp_server_module.AsyncSessionLocal
+    mcp_server_module.AsyncSessionLocal = test_session_factory
+    yield
+    mcp_server_module.AsyncSessionLocal = original
+    await engine.dispose()
+
+
 @pytest.fixture
 async def db_session():
     engine = make_test_engine()

backend/tests/test_mcp.py

@@ -0,0 +1,56 @@
+import json
+import pytest
+from app.api.mcp_server import (
+    get_todos, create_todo, update_todo, postpone_todo, delete_todo,
+)
+
+
+async def test_get_todos_retourne_liste_json():
+    result = await get_todos(status="pending")
+    data = json.loads(result)
+    assert isinstance(data, list)
+
+
+async def test_create_todo_outil_cree_une_tache():
+    result = await create_todo(title="TEST_MCP_todo_create")
+    data = json.loads(result)
+    assert data["title"] == "TEST_MCP_todo_create"
+    assert data["status"] == "pending"
+    assert data["priority"] == "medium"
+    # Cleanup
+    await delete_todo(id=str(data["id"]))
+
+
+async def test_update_todo_outil():
+    created = json.loads(await create_todo(title="TEST_MCP_todo_update"))
+    result = await update_todo(id=str(created["id"]), status="done")
+    data = json.loads(result)
+    assert data["status"] == "done"
+    await delete_todo(id=str(created["id"]))
+
+
+async def test_postpone_todo_outil():
+    created = json.loads(await create_todo(title="TEST_MCP_todo_postpone"))
+    result = await postpone_todo(id=str(created["id"]), days=3)
+    data = json.loads(result)
+    assert data["postponed_count"] == 1
+    await delete_todo(id=str(created["id"]))
+
+
+async def test_delete_todo_outil():
+    created = json.loads(await create_todo(title="TEST_MCP_todo_delete"))
+    result = await delete_todo(id=str(created["id"]))
+    data = json.loads(result)
+    assert "deleted" in data
+
+
+async def test_update_todo_id_invalide():
+    result = await update_todo(id="pas-un-uuid", title="x")
+    data = json.loads(result)
+    assert "error" in data
+
+
+async def test_delete_todo_introuvable():
+    result = await delete_todo(id="00000000-0000-0000-0000-000000000000")
+    data = json.loads(result)
+    assert "error" in data