fix(test): add cleanup fixture and no_parallel mark for MCP tests

[jquinter]

Summary

Fixes two MCP server test failures when running with pytest-xdist parallel execution (--dist=loadscope):

• test_mcp_routing_with_conflicting_alias_and_group_name
• test_oauth2_headers_passed_to_mcp_client

Problem

Both tests were failing with:

AssertionError: Should have resolved to exactly one server. (got 0 servers)
AssertionError: Expected _create_mcp_client to be called once (call_count was 0)

Root cause: These tests rely on global_mcp_server_manager singleton state and complex async mocking patterns. When running with parallel execution:

• Each worker process may have different singleton instances
• Patches applied in one worker don't affect code running in another
• Global state can leak between tests running in the same worker

Solution

Two-pronged approach:

1. Added autouse fixture for state cleanup

@pytest.fixture(autouse=True)
def cleanup_mcp_global_state():
    """Clean up MCP global state before and after each test."""
    global_mcp_server_manager.registry.clear()
    yield
    global_mcp_server_manager.registry.clear()

This ensures proper isolation even when tests run sequentially in the same worker.

2. Added @pytest.mark.no_parallel

Marked these specific tests to run sequentially rather than in parallel:

@pytest.mark.no_parallel
async def test_mcp_routing_with_conflicting_alias_and_group_name():

This prevents the parallel execution issues while still allowing other tests in the file to benefit from parallelization.

Testing

• Tested locally with serial execution: pytest tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_server.py -v
• Verified tests pass with fixture but without no_parallel mark (when run individually)
• Confirmed that global state cleanup prevents test pollution

Related

• Fixes test failures exposed by PR improve(ci): enhance test stability with better isolation and distribution #21277 (CI improvements with better test isolation)
• Not caused by PR improve(ci): enhance test stability with better isolation and distribution #21277, but exposed by improved test distribution with --dist=loadscope

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Feb 16, 2026 3:14pm

[greptile-apps]

Greptile Summary

This PR adds test isolation improvements for MCP server tests that were failing under pytest-xdist parallel execution. The changes consist of:

• An autouse fixture that clears global_mcp_server_manager.registry before and after each test, preventing state leakage between tests sharing the same worker process
• @pytest.mark.no_parallel markers on test_mcp_routing_with_conflicting_alias_and_group_name and test_oauth2_headers_passed_to_mcp_client, which directly manipulate the global singleton via patch.object

The cleanup fixture is the substantive fix — it ensures proper isolation regardless of execution order. The no_parallel mark is registered in pyproject.toml but does not appear to be enforced by any conftest or pytest plugin in the test runner configuration (the Makefile uses -n 4 without --dist=loadscope). The mark serves as documentation/intent rather than enforcement, though --dist=loadscope (mentioned in the PR description) would group tests by module, making the mark less critical. No real network calls are introduced — all tests remain mock-based.

Confidence Score: 4/5

• This PR is safe to merge — it only modifies test infrastructure with no production code changes.
• The changes are limited to test fixtures and markers in a single test file. The autouse cleanup fixture is correctly implemented with proper ImportError handling. No production code is touched. The only minor concern is that the cleanup fixture doesn't cover all mutable global state attributes (only registry), but this is sufficient for the current test suite.
• No files require special attention. The single changed file is a test file with straightforward fixture and marker additions.

Important Files Changed

Filename	Overview
tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_server.py	Adds autouse cleanup fixture for global_mcp_server_manager.registry and @pytest.mark.no_parallel on two tests to improve test isolation with pytest-xdist. The cleanup fixture is well-structured with proper try/except for ImportError. Minor observation: the no_parallel mark is not enforced by any conftest or plugin - the real fix is the cleanup fixture.

Flowchart

flowchart TD
    A[Test starts] --> B[cleanup_mcp_global_state fixture: clear registry]
    B --> C{Test has no_parallel mark?}
    C -->|Yes| D[Run sequentially in xdist]
    C -->|No| E[May run in parallel with xdist]
    D --> F[Test executes with clean global state]
    E --> F
    F --> G[Test manipulates global_mcp_server_manager.registry]
    G --> H[Test assertions]
    H --> I[cleanup_mcp_global_state teardown: clear registry]
    I --> J[Test ends - clean state for next test]

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