How to implement pytest for FastAPI with MongoDB(Motor)

Question

I want to write tests for my FastAPI endpoints

example for my code:

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()

@app.get("/todos")
async def get_todo_by_title(title: str,current_user: User = Depends(get_current_user))
    document = await collection.find_one({"title": title})
    return document

client = TestClient(app)

def test_get_todo_by_title():
    response = client.get("/todos")
    assert response.status_code == 200

What the best way to test my endpoints?

I want to use fake DB for testing, something like json file

db = {
todos: [...]
}