httpx Add server.url property in tests (Fix)

The Fix

Upgrade to version 0.7.3 or later.

Based on closed encode/httpx issue #288 · PR/commit linked

Production note: Most teams hit this during upgrades or environment changes. Roll out with a canary and smoke critical endpoints (health, OpenAPI/docs) before 100%.

Jump to Verify Open PR/Commit

@@ -81,7 +81,7 @@ def __init__(
                 dispatch = WSGIDispatch(app=app)
             else:
-                dispatch = ASGIDispatch(app=app)
+                dispatch = ASGIDispatch(app=app, backend=backend)

repro.py

# tests/client/test_async_client.py

async def test_get(server, backend):
    url = "http://127.0.0.1:8000/"
    async with httpx.AsyncClient(backend=backend) as client:
        response = await client.get(url)
    # ...

async def test_raise_for_status(server, backend):
    async with httpx.AsyncClient(backend=backend) as client:
        for status_code in (200, 400, 404, 500, 505):
            response = await client.request(
                "GET", f"http://127.0.0.1:8000/status/{status_code}"
            )
        # ...

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

fix.md

Option A — Upgrade to fixed release\nUpgrade to version 0.7.3 or later.\nWhen NOT to use: Do not use this fix if the server URL needs to be different for each test case.\n\n

Why This Fix Works in Production

Trigger: for status_code in (200, 400, 404, 500, 505):
Mechanism: The URL for the uvicorn server was hardcoded in multiple test locations
Why the fix works: Added a server.url property to streamline URL management in tests, allowing for easier updates and cleaner code. (first fixed release: 0.7.3).

Production impact:

If left unfixed, the same config can fail only in production (env differences), causing startup failures or partial feature outages.

Why This Breaks in Prod

The URL for the uvicorn server was hardcoded in multiple test locations
Production symptom (often without a traceback): for status_code in (200, 400, 404, 500, 505):

Proof / Evidence

GitHub issue: #288
Fix PR: https://github.com/encode/httpx/pull/276
First fixed release: 0.7.3
Reproduced locally: No (not executed)
Last verified: 2026-02-09
Confidence: 0.75
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.57

Discussion

High-signal excerpts from the issue thread (symptoms, repros, edge-cases).

Jump to Sources Open on GitHub

“We are defining the URL to the uvicorn server that's running during our tests in lots of place, e.g.: As suggested by @sethmlarson in https://github.com/encode/httpx/pull/276#issuecomment-525445494, it would be better to use a URL property”

Issue thread · issue description · source

Failure Signature (Search String)

for status_code in (200, 400, 404, 500, 505):

Copy-friendly signature

signature.txt

Failure Signature
-----------------
for status_code in (200, 400, 404, 500, 505):

Error Message

Signature-only (no traceback captured)

error.txt

Error Message
-------------
for status_code in (200, 400, 404, 500, 505):

Minimal Reproduction

repro.py

# tests/client/test_async_client.py

async def test_get(server, backend):
    url = "http://127.0.0.1:8000/"
    async with httpx.AsyncClient(backend=backend) as client:
        response = await client.get(url)
    # ...

async def test_raise_for_status(server, backend):
    async with httpx.AsyncClient(backend=backend) as client:
        for status_code in (200, 400, 404, 500, 505):
            response = await client.request(
                "GET", f"http://127.0.0.1:8000/status/{status_code}"
            )
        # ...

What Broke

Tests were difficult to maintain due to hardcoded server URLs, leading to potential inconsistencies.

Why It Broke

The URL for the uvicorn server was hardcoded in multiple test locations

Fix Options (Details)

Option A — Upgrade to fixed release Safe default (recommended)

Upgrade to version 0.7.3 or later.

When NOT to use: Do not use this fix if the server URL needs to be different for each test case.

Use when you can deploy the upstream fix. It is usually lower-risk than long-lived workarounds.

Fix reference: https://github.com/encode/httpx/pull/276

First fixed release: 0.7.3

Last verified: 2026-02-09. Validate in your environment.

When NOT to Use This Fix

Do not use this fix if the server URL needs to be different for each test case.

Verify Fix

verify

Re-run the minimal reproduction on your broken version, then apply the fix and re-run.

Did This Fix Work in Your Case?

Quick signal helps us prioritize which fixes to verify and improve.

Prevention

Add a CI check that diffs key outputs after upgrades (OpenAPI schema snapshots, JSON payload shapes, CLI output).
Upgrade behind a canary and run integration tests against the canary before 100% rollout.

Version Compatibility Table

Version	Status
0.7.3	Fixed

Related Issues

No related fixes found.

Cluster: httpx:configuration-error All hubs All clusters

Related clusters: Data consistency Other Timeout

Sources

We don’t republish the full GitHub discussion text. Use the links above for context.