Testing Events: lifespan and startup - shutdown¶
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When you need lifespan
to run in your tests, you can use the TestClient
with a with
statement:
from contextlib import asynccontextmanager
from fastapi import FastAPI
from fastapi.testclient import TestClient
items = {}
@asynccontextmanager
async def lifespan(app: FastAPI):
items["foo"] = {"name": "Fighters"}
items["bar"] = {"name": "Tenders"}
yield
# clean up items
items.clear()
app = FastAPI(lifespan=lifespan)
@app.get("/items/{item_id}")
async def read_items(item_id: str):
return items[item_id]
def test_read_items():
# Before the lifespan starts, "items" is still empty
assert items == {}
with TestClient(app) as client:
# Inside the "with TestClient" block, the lifespan starts and items added
assert items == {"foo": {"name": "Fighters"}, "bar": {"name": "Tenders"}}
response = client.get("/items/foo")
assert response.status_code == 200
assert response.json() == {"name": "Fighters"}
# After the requests is done, the items are still there
assert items == {"foo": {"name": "Fighters"}, "bar": {"name": "Tenders"}}
# The end of the "with TestClient" block simulates terminating the app, so
# the lifespan ends and items are cleaned up
assert items == {}
You can read more details about the "Running lifespan in tests in the official Starlette documentation site."
For the deprecated startup
and shutdown
events, you can use the TestClient
as follows:
from fastapi import FastAPI
from fastapi.testclient import TestClient
app = FastAPI()
items = {}
@app.on_event("startup")
async def startup_event():
items["foo"] = {"name": "Fighters"}
items["bar"] = {"name": "Tenders"}
@app.get("/items/{item_id}")
async def read_items(item_id: str):
return items[item_id]
def test_read_items():
with TestClient(app) as client:
response = client.get("/items/foo")
assert response.status_code == 200
assert response.json() == {"name": "Fighters"}