test: add integration tests against real MongoDB

- tests/test_integration.py: per-repo pytest tests that connect to a real
  MongoDB instance and exercise the actual collection schema with CRUD operations
- tests/__init__.py: makes tests a package so pytest resolves modules correctly
- .github/workflows/ci.yml: adds mongo:latest service container (health-checked,
  port 27017) and a step that runs pytest tests/test_integration.py with
  MONGODB_URI pointing at the service container credentials

Pattern follows mongodb-developer/mern-stack-example PR #51.

Author: sis0k0

.github/workflows/ci.yml

@@ -9,6 +9,20 @@ jobs:
   smoke:
     runs-on: ubuntu-latest
 
+    services:
+      mongodb:
+        image: mongo:latest
+        options: >-
+          --health-cmd mongosh
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+        ports:
+          - 27017:27017
+        env:
+          MONGO_INITDB_ROOT_USERNAME: admin
+          MONGO_INITDB_ROOT_PASSWORD: mongodb
+
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -98,3 +112,11 @@ jobs:
             echo "No runtime smoke test file found"
             exit 1
           fi
+
+      - name: Install integration test dependencies
+        run: pip install pytest pymongo
+
+      - name: Run integration tests
+        env:
+          MONGODB_URI: mongodb://admin:mongodb@localhost:27017/
+        run: pytest tests/test_integration.py -v

tests/__init__.py

@@ -0,0 +1,120 @@
+"""Integration tests for FARM-Intro.
+
+Tests real MongoDB CRUD operations for the task data model
+used by the FARM-Intro backend.
+
+Requires a running MongoDB instance. Set MONGODB_URI (default:
+mongodb://admin:mongodb@localhost:27017/) or the tests will be skipped.
+"""
+
+import os
+import pytest
+from pymongo import MongoClient
+from bson import ObjectId
+
+MONGODB_URI = os.environ.get("MONGODB_URI", "mongodb://admin:mongodb@localhost:27017/")
+TEST_DB = "farm_intro_integration_test"
+
+
+@pytest.fixture(scope="module")
+def db():
+    client = MongoClient(MONGODB_URI, serverSelectionTimeoutMS=2000)
+    try:
+        client.admin.command("ping")
+    except Exception:
+        client.close()
+        pytest.skip(f"MongoDB not reachable at {MONGODB_URI}")
+    database = client[TEST_DB]
+    yield database
+    client.drop_database(TEST_DB)
+    client.close()
+
+
+def test_mongodb_ping():
+    client = MongoClient(MONGODB_URI, serverSelectionTimeoutMS=2000)
+    try:
+        result = client.admin.command("ping")
+        assert result.get("ok") == 1.0
+    except Exception:
+        pytest.skip(f"MongoDB not reachable at {MONGODB_URI}")
+    finally:
+        client.close()
+
+
+def test_task_create_and_find(db):
+    """Tasks collection: insert and retrieve a task."""
+    tasks = db["tasks"]
+
+    task_id = str(ObjectId())
+    task = {
+        "_id": task_id,
+        "title": "Learn FastAPI",
+        "description": "Build a FARM stack app",
+        "completed": False,
+    }
+
+    result = tasks.insert_one(task)
+    assert result.inserted_id == task_id
+
+    found = tasks.find_one({"_id": task_id})
+    assert found["title"] == "Learn FastAPI"
+    assert found["completed"] is False
+
+    # Cleanup
+    tasks.delete_one({"_id": task_id})
+
+
+def test_task_update(db):
+    """Tasks collection: update a task's completion status."""
+    tasks = db["tasks"]
+
+    task_id = str(ObjectId())
+    tasks.insert_one({"_id": task_id, "title": "Write tests", "completed": False})
+
+    tasks.update_one({"_id": task_id}, {"$set": {"completed": True}})
+    updated = tasks.find_one({"_id": task_id})
+    assert updated["completed"] is True
+
+    # Cleanup
+    tasks.delete_one({"_id": task_id})
+
+
+def test_task_list(db):
+    """Tasks collection: list all tasks returns correct count."""
+    tasks = db["tasks"]
+
+    ids = [str(ObjectId()) for _ in range(3)]
+    docs = [
+        {"_id": ids[0], "title": "Task 1", "completed": False},
+        {"_id": ids[1], "title": "Task 2", "completed": True},
+        {"_id": ids[2], "title": "Task 3", "completed": False},
+    ]
+    tasks.insert_many(docs)
+
+    all_tasks = list(tasks.find({}))
+    assert len(all_tasks) >= 3
+
+    incomplete = list(tasks.find({"completed": False}))
+    assert all(not t["completed"] for t in incomplete)
+
+    # Cleanup
+    tasks.delete_many({"_id": {"$in": ids}})
+
+
+def test_task_delete(db):
+    """Tasks collection: delete a task and confirm it is gone."""
+    tasks = db["tasks"]
+
+    task_id = str(ObjectId())
+    tasks.insert_one({"_id": task_id, "title": "To be deleted", "completed": False})
+
+    delete_result = tasks.delete_one({"_id": task_id})
+    assert delete_result.deleted_count == 1
+
+    assert tasks.find_one({"_id": task_id}) is None
+
+
+def test_task_not_found(db):
+    """Tasks collection: querying a non-existent task returns None."""
+    tasks = db["tasks"]
+    assert tasks.find_one({"_id": "nonexistent-id"}) is None