uvicorn Lifespan tests are broken (Fix)

The Fix

Fix lifespan tests that were silently failing by correcting the assert scope shape.

Based on closed Kludex/uvicorn issue #911 · PR/commit linked

Jump to Verify Open PR/Commit

@@ -146,26 +146,33 @@ async def test():
 
 
[email protected]("mode", ("auto", "on"))
-def test_lifespan_scope_asgi3app(mode):
+def test_lifespan_scope_asgi3app():

repro.py

@pytest.mark.parametrize("mode", ("auto", "on"))
def test_lifespan_scope_asgi3app(mode):
    async def asgi3app(scope, receive, send):
        assert scope == {"version": "3.0", "spec_version": "2.0"}

    async def test():
        config = Config(app=asgi3app, lifespan=mode)
        lifespan = LifespanOn(config)

        await lifespan.startup()
        await lifespan.shutdown()

    loop = asyncio.new_event_loop()
    loop.run_until_complete(test())

verify

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

fix.md

Option A — Apply the official fix\nFix lifespan tests that were silently failing by correcting the assert scope shape.\nWhen NOT to use: This fix is not applicable if the test assertions are intended to validate different scope shapes.\n\n

Why This Fix Works in Production

Trigger: Testing started at 2:47 PM ...
Mechanism: The lifespan tests were incorrectly asserting the shape of the scope dictionary

Production impact:

If left unfixed, this can cause silent data inconsistencies that propagate (bad cache entries, incorrect downstream decisions).

Why This Breaks in Prod

Shows up under Python 3.8.5 in real deployments (not just unit tests).
The lifespan tests were incorrectly asserting the shape of the scope dictionary
Surfaces as: /home/lotso/PycharmProjects/uvicorn/venv/bin/python /home/lotso/.local/share/JetBrains/Toolbox/apps/PyCharm-P/ch-0/203.5981.165/plugins/python/helpers/pycharm/_jb_pytest_runner.py…

Proof / Evidence

GitHub issue: #911
Fix PR: https://github.com/kludex/uvicorn/pull/913
Reproduced locally: No (not executed)
Last verified: 2026-02-12
Confidence: 0.70
Did this fix it?: Yes (upstream fix exists)
Own content ratio: 0.38

Discussion

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

Jump to Sources Open on GitHub

“### Checklist  - [x] The bug is reproducible against the latest release and/or master. - [x] There are no similar issues or pull requests to fix it yet. #”

Issue thread · issue description · source

Failure Signature (Search String)

Testing started at 2:47 PM ...

Error Message

Stack trace

error.txt

Error Message
-------------
/home/lotso/PycharmProjects/uvicorn/venv/bin/python /home/lotso/.local/share/JetBrains/Toolbox/apps/PyCharm-P/ch-0/203.5981.165/plugins/python/helpers/pycharm/_jb_pytest_runner.py --target test_lifespan.py::test_lifespan_scope_asgi3app
Testing started at 2:47 PM ...
Launching pytest with arguments test_lifespan.py::test_lifespan_scope_asgi3app in /home/lotso/PycharmProjects/uvicorn/tests

============================= test session starts ==============================
platform linux -- Python 3.8.5, pytest-6.2.0, py-1.10.0, pluggy-0.13.1 -- /home/lotso/PycharmProjects/uvicorn/venv/bin/python
cachedir: .pytest_cache
rootdir: /home/lotso/PycharmProjects/uvicorn, configfile: setup.cfg
plugins: reraise-1.0.3, asyncio-0.14.0
collecting ... collected 2 items

test_lifespan.py::test_lifespan_scope_asgi3app[auto] 
test_lifespan.py::test_lifespan_scope_asgi3app[on] 

============================== 2 passed in 0.11s ===============================

Process finished with exit code 0
PASSED              [ 50%]INFO:     Waiting for application startup.
INFO:     ASGI 'lifespan' protocol appears unsupported.
INFO:     Application startup complete.
PASSED                [100%]INFO:     Waiting for application startup.
ERROR:    Exception in 'lifespan' protocol
Traceback (most recent call last):
  File "/home/lotso/PycharmProjects/uvicorn/uvicorn/lifespan/on.py", line 55, in main
    await app
... (truncated) ...

Minimal Reproduction

repro.py

@pytest.mark.parametrize("mode", ("auto", "on"))
def test_lifespan_scope_asgi3app(mode):
    async def asgi3app(scope, receive, send):
        assert scope == {"version": "3.0", "spec_version": "2.0"}

    async def test():
        config = Config(app=asgi3app, lifespan=mode)
        lifespan = LifespanOn(config)

        await lifespan.startup()
        await lifespan.shutdown()

    loop = asyncio.new_event_loop()
    loop.run_until_complete(test())

Environment

Python: 3.8.5

What Broke

Lifespan tests passed when they should have failed, leading to false positives in test results.

Why It Broke

The lifespan tests were incorrectly asserting the shape of the scope dictionary

Fix Options (Details)

Option A — Apply the official fix

Fix lifespan tests that were silently failing by correcting the assert scope shape.

When NOT to use: This fix is not applicable if the test assertions are intended to validate different scope shapes.

Fix reference: https://github.com/kludex/uvicorn/pull/913

Last verified: 2026-02-12. Validate in your environment.

When NOT to Use This Fix

This fix is not applicable if the test assertions are intended to validate different scope shapes.

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

Capture the exact failing error string in logs and tests so you can reproduce via a minimal script.
Pin production dependencies and upgrade only with a reproducible test that hits the failing path.

Related Issues

No related fixes found.

Cluster: uvicorn:data-consistency All hubs All clusters

Related clusters: Configuration error Race condition SSL handshake

Sources

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