Starting a FastAPI as a server mock

0_README.md

Using FastAPI as Server Mock

I wanted to start a real mock server with real instances that I could fine tune for my own needs.

I found a way to start the FastAPI to run the tests agains it, and then kill the uvicorn.

Here an example code 👍

main.py

from fastapi import FastAPI
from starlette.requests import Request
from starlette.responses import StreamingResponse
from starlette.background import BackgroundTask
import httpx

app = FastAPI()

@app.get("/example")
async def example():
    client = httpx.AsyncClient(base_url="https://myotherprovider.com")
    response = await client.get("/v1/example")
    return response.json()

test_main.py

import time
import uvicorn
import pytest
from multiprocessing import Process
from fastapi.testclient import TestClient
from fastapi import FastAPI
from .main import app, client as c

client = TestClient(app)

mock_port = 7232
open_api_mock = FastAPI()
open_api_mock.add_api_route("/v1/example",
                            lambda: {"message": "Hello World"},
                            methods=["GET"])
c.base_url = "http://localhost:" + str(mock_port)


def start_server():
    uvicorn.run(open_api_mock,
                host="0.0.0.0",
                port=mock_port)


@pytest.fixture(scope="session", autouse=True)
def setup():
    proc = Process(target=start_server, args=())
    proc.start()
    time.sleep(1)
    yield
    proc.terminate()


def test_read_main():
    response = client.get("/example")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello World"}