test(fastmcp): Use AsyncClient for SSE

[alexander-alderman-webb]

Description

Stop mocking transport layer of mcp package in tests.

The SSE server and client are run in-process by using an in-memory object queue to pass messages.

Issues

Reminders

• Please add tests to validate your changes, and lint your code using tox -e linters.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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New Features ✨

Span Streaming

• feat(span-streaming): Add spans to telemetry pipeline, add span name and attributes (3) by sentrivana in #5399
• feat(span-streaming): Add span batcher (2) by sentrivana in #5398
• feat(span-streaming): Add experimental trace_lifecycle switch (1) by sentrivana in #5397

Bug Fixes 🐛

Span Streaming

• fix(span-streaming): Always preserialize attributes by sentrivana in #5407
• fix(span-streaming): Warn about thread usage if any batcher is active by sentrivana in #5408

Other

• fix(arq): handle settings_cls passed as keyword argument by nc9 in #5393
• fix(dramatiq): cleanup isolated scope and transaction when message is skipped by frankie567 in #5346
• fix(google-genai): deactivate google genai when langchain is used by shellmayr in #5389

Internal Changes 🔧

Fastmcp

• test(fastmcp): Use AsyncClient for SSE by alexander-alderman-webb in #5400

• test(fastmcp): Use TestClient for Streamable HTTP by alexander-alderman-webb in #5384
• test(fastmcp): Simulate stdio transport with memory streams by alexander-alderman-webb in #5333

Mcp

• test(mcp): Use AsyncClient for SSE by alexander-alderman-webb in #5396
• test(mcp): Use TestClient for Streamable HTTP by alexander-alderman-webb in #5383
• test(mcp): Remove unused stdio helpers by alexander-alderman-webb in #5409
• test(mcp): Simulate stdio transport with memory streams by alexander-alderman-webb in #5329

Other

• ci: migration to the new codecov action by MathurAditya724 in #5392

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[sentrivana]

🥔

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[sentry]

Bug: The test fixture json_rpc_sse uses create_memory_object_stream[bytes](0), which is AnyIO 4.0+ syntax. However, tox.ini constrains test environments to AnyIO < 4.0, causing a TypeError.
_{Severity: HIGH}

Suggested Fix

Revert the call at tests/conftest.py:842 to use the AnyIO 3.x compatible syntax: create_memory_object_stream(0). This will align the code with the version constraints specified in tox.ini and ensure the tests can run successfully in the configured environments.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: tests/conftest.py#L842

Potential issue: The code at `tests/conftest.py:842` uses
`create_memory_object_stream[bytes](0)`, a syntax valid only for AnyIO version 4.0 and
later. However, the project's `tox.ini` configuration explicitly pins AnyIO to versions
below 4.0.0 for several test environments, including `fastapi` and `starlette`. When
tests are executed in these environments, an older version of AnyIO will be installed.
This will cause a `TypeError: 'function' object is not subscriptable` at runtime because
the AnyIO 3.x version of `create_memory_object_stream` does not support subscripting.
This will cause tests that rely on the `json_rpc_sse` fixture to fail.