can't use test client in pytest with add_exception_handler or add_middleware

[markqiu]

Describe the bug
Can't use test client in pytest with add_exception_handler or add_middleware called before. After called add_exception_handler or add_middleware, test_client.get or test.client.put etc always returns 200.

To Reproduce
Steps to reproduce the behavior:

from fastapi import FastAPI
from starlette.middleware.cors import CORSMiddleware
from starlette.status import HTTP_422_UNPROCESSABLE_ENTITY

app = FastAPI(title=PROJECT_NAME)

user = {
    "user": {
        "email": "user@example.com",
        "password": "string",
        "username": "string"
    }
}


from starlette.testclient import TestClient
client = TestClient(app)


@app.get("/text")
def get_text():
    return "Hello World"


def test_update_current_user():
    app.add_middleware(
         CORSMiddleware,
         allow_origins=ALLOWED_HOSTS,
         allow_credentials=True,
         allow_methods=["*"],
         allow_headers=["*"],
    )
    app.add_exception_handler(HTTPException, http_error_handler)
    app.add_exception_handler(HTTP_422_UNPROCESSABLE_ENTITY, 
    http_422_error_handler)
    response = client.get("/user1")  # which should failed and return 404
    assert response.status_code == 200

Environment:

• OS: macOS

• FastAPI Version: '0.29.0'

• Python version
  3.7

[tiangolo]

I imagine you were able to solve your problem, thanks for closing the issue. Feel free to add more comments or create new issues.