Bad encoding in query parameters with new TestClient using httpx.Client

[Kludex]

Discussed in #1946

^{Originally posted by azogue November 15, 2022}
After the change to httpx for the TestClient in v0.21.0 (), the query parameters are not properly encoded? when sending requests with it, and strings are corrupted when received in the endpoints.

Quick example to show the problem:

import logging
from fastapi import FastAPI

app = FastAPI()

@app.get("/example")
async def _show_encoding_error(look_for: str):
    return {"found": look_for}

if __name__ == '__main__':
    from starlette.testclient import TestClient

    with TestClient(app) as client:
        params = {"look_for": "plain text"}
        resp = client.get("/example", params=params).json()
        logging.warning(resp)
        assert resp["found"] == "plain text"

        params = {"look_for": "España"}
        resp = client.get("/example", params=params).json()
        logging.warning(resp)
        assert resp["found"] == "España", resp["found"]

The example app works as expected if called from the SwaggerUI or from another python process using a plain httpx.Client, so it appears something broke with the new wrapping for TestClient 🥲

import httpx

params = {"look_for": "España"}
with httpx.Client(base_url="http://localhost:8000/") as client:
    resp = client.get("/example", params=params).json()
    assert resp["found"] == "España"

Details

First issued in fastapi repo: fastapi/fastapi#5646, before checking the TestClient comes from here 🙈

Environment:

• macOS M1 arm64
• fastapi v0.87.0
• starlette v0.21.0
• httpx v0.23.0

[azogue]

I just checked that removing both unquote operations for the netloc and the query parts does work as expected and does not break any of the tests 🥳 (609 passed, 2 xfailed in 2.41s in quick venv with py3.10)

So it could be as simple as that to fix this 🤩

[Kludex]

This was fixed on #1953 , and it will be available on Starlette 0.22.0.