Test CI stability

[jlowin]

(due to issues with the release/2.x branch, this had to be deleted and replaced with #2696)

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Uvicorn 0.39.0 introduced a fix for ContextVars pollution (encode/uvicorn#2742) that wraps ASGI tasks in empty contexts. This is a workaround for a CPython bug (python/cpython#140947) being fixed in Python 3.13+.

The context isolation breaks task cancellation propagation, causing test cleanup to hang when we task.cancel() and await task on uvicorn server tasks.

Fix: Use graceful shutdown (server.should_exit = True) for real uvicorn servers, and add timeouts for mocked server cleanup.

Files changed:

• tests/server/test_logging.py - Add timeout to mocked server cleanup
• tests/client/test_streamable_http.py - Use graceful shutdown for nested_server fixture
• tests/client/test_sse.py - Use graceful shutdown for nested_sse_server fixture

[marvin-context-protocol]

Test Failure Analysis

Summary: CI is failing due to pre-existing resource task test failures, not the Uvicorn 0.39+ cleanup fixes in this PR.

Root Cause: All tests in tests/client/tasks/test_client_resource_tasks.py are failing with McpError: 'document'. This failure exists on the base branch (release/2.x) and is unrelated to the changes in this PR. The 6 resource task tests account for the CI failures across all 5 workflow jobs.

Suggested Solution:

1. Skip or fix the failing resource task tests - The error McpError: 'document' suggests a server-side issue with task-enabled resources. This needs investigation separate from this PR.

2. Verify the PR changes work correctly - The actual changes in this PR (test cleanup for Uvicorn 0.39+) pass successfully:

   • ✅ tests/server/test_logging.py (3 tests)
   • ✅ tests/client/test_streamable_http.py (13 tests)
   • ✅ tests/client/test_sse.py (8 tests)

To proceed with this PR: Either fix the resource task tests or temporarily skip them with @pytest.mark.skip to unblock this important Uvicorn 0.39+ compatibility fix.

Detailed Analysis

Failing Tests (Pre-existing on base branch)

All 6 tests in tests/client/tasks/test_client_resource_tasks.py fail with:

mcp.shared.exceptions.McpError: 'document'

The error originates from the MCP SDK when the server returns a JSON-RPC error response. The error message is just the string 'document' (the resource function name), suggesting the server-side task execution for resources is broken.

Tests Modified by This PR (All Passing)

The PR correctly fixes test cleanup issues caused by Uvicorn 0.39.0's context isolation changes:

For real Uvicorn servers (test_sse.py, test_streamable_http.py):

• Changed from: task.cancel() + catching CancelledError
• Changed to: server.should_exit = True + await task
• ✅ This is the correct approach - Uvicorn 0.39+ wraps ASGI tasks in empty contexts to work around a CPython bug, which breaks cancellation propagation

For mocked servers (test_logging.py):

• Added: asyncio.wait_for(task, timeout=2.0) with timeout protection
• Added: Signal to finish before canceling
• ✅ This prevents hangs when mocks don't respond to cancellation

Local Test Results

$ uv run pytest tests/server/test_logging.py tests/client/test_streamable_http.py tests/client/test_sse.py -v
======================== 22 passed, 1 xfailed in 10.35s ========================

All tests modified by this PR pass successfully on Linux.

Related Files

Modified by PR (all passing):

• tests/server/test_logging.py - Mocked Uvicorn server cleanup
• tests/client/test_streamable_http.py - Real Uvicorn server cleanup for HTTP transport
• tests/client/test_sse.py - Real Uvicorn server cleanup for SSE transport

Failing (pre-existing issue):

• tests/client/tasks/test_client_resource_tasks.py - Resource task execution broken
• src/fastmcp/server/resources/ - Likely source of the McpError issue
• src/fastmcp/client/client.py - Resource task client methods