I wanted to start an actual server process, run it for the duration of my pytest session and shut it down at the end.
Here's the recipe I came up with. This fixture lives in
import pytest import sqlite_utils import subprocess @pytest.fixture(scope="session") def ds_server(tmp_path_factory): db_directory = tmp_path_factory.mktemp("dbs") db_path = db_directory / "test.db" db = sqlite_utils.Database(db_path) insert_test_data(db) ds_proc = subprocess.Popen( [ "datasette", str(db_path), "-p", "8041" ], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, ) # Give the server time to start time.sleep(2) # Check it started successfully assert not ds_proc.poll(), ds_proc.stdout.read().decode("utf-8") yield ds_proc # Shut it down at the end of the pytest session ds_proc.terminate()
A test looks like this:
import httpx def test_server_starts(ds_server): response = httpx.get("http://127.0.0.1:8041/") assert response.status_code == 200
While adding tests to Datasette Lite I found myself needing to run a localhost server that served static files directly.
I completely forgot about this TIL, and instead took inspiration from pytest-simplehttpserver - coming up with this pattern:
from subprocess import Popen, PIPE import pathlib import pytest import time from http.client import HTTPConnection root = pathlib.Path(__file__).parent.parent.absolute() @pytest.fixture(scope="module") def static_server(): process = Popen( ["python", "-m", "http.server", "8123", "--directory", root], stdout=PIPE ) retries = 5 while retries > 0: conn = HTTPConnection("localhost:8123") try: conn.request("HEAD", "/") response = conn.getresponse() if response is not None: yield process break except ConnectionRefusedError: time.sleep(1) retries -= 1 if not retries: raise RuntimeError("Failed to start http server") else: process.terminate() process.wait()
static_server as a fixture is enough to ensure requests to
http://localhost:8123/ will be served by that temporary server.
I like how this version polls for a successful HEAD request (a trick inspired by
pytest-simplehttpserver) rather than just sleeping.
Created 2020-08-31T19:06:36-07:00, updated 2022-07-22T18:20:37-07:00 · History · Edit