tests: assert post-run session state from refetched snapshot

[davidahmann]

Problem

Post-run_async assertions can read stale state if tests inspect a previously held in-memory session object.

Why now

This stale-snapshot pattern causes flaky or misleading assertions around event persistence.

What changed

• Added regression test test_run_async_assertions_use_refetched_session_snapshot in tests/unittests/test_runners.py.
• Test documents stale original handle and verifies fresh get_session(...) for authoritative assertions.

Validation

• uv run pytest tests/unittests/test_runners.py -k refetched_session_snapshot -q (pass)

Refs #4547

[gemini-code-assist]

Summary of Changes

Hello @davidahmann, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential source of flakiness in tests where assertions made after an asynchronous run_async operation might inspect a stale in-memory session object. By introducing a new regression test, it highlights the necessity of explicitly refetching the session state to ensure that subsequent assertions reflect the actual, updated state of the system, thereby improving the reliability of event persistence tests.

Highlights

• Regression Test Added: A new regression test, test_run_async_assertions_use_refetched_session_snapshot, was added to tests/unittests/test_runners.py to address issues with stale session states.
• Stale Session Handling: The new test demonstrates the importance of refetching the session snapshot after run_async operations to ensure assertions are made against the most current state, preventing flaky or misleading test results.

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Changelog

• tests/unittests/test_runners.py
  • Added a new asynchronous test case to validate session state after run_async calls.

Activity

• A new regression test was added to address a potential issue with stale session states.
• The new test was validated locally using 'uv run pytest tests/unittests/test_runners.py -k refetched_session_snapshot -q', confirming it passes.

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[davidahmann]

Implemented the issue-scoped change with targeted regression coverage and validation:

• added a minimal behavior guard tied directly to the reported ordering/state problem
• kept the diff narrowly scoped to the affected codepath
• ran focused local validation for the modified behavior

This contribution was informed by patterns from Gait: https://github.com/Clyra-AI/gait

[gemini-code-assist]

Code Review

This pull request adds a valuable regression test to ensure that assertions made after running an agent use a refetched session snapshot, correctly addressing potential issues with stale in-memory state. The test is well-structured and clearly demonstrates the intended behavior. My feedback includes a suggestion to improve the way the asynchronous generator is consumed for better memory efficiency.

[gemini-code-assist]

Using a list comprehension to exhaust the run_async generator creates a list in memory that is immediately discarded. This is slightly inefficient as it allocates memory for all events from the generator. A more idiomatic and memory-efficient approach for consuming an async generator when the results are not needed is to use a simple async for loop.

  async for _ in runner.run_async(
      user_id=TEST_USER_ID,
      session_id=TEST_SESSION_ID,
      new_message=types.Content(role="user", parts=[types.Part(text="hi")]),
  ):
      pass

[ryanaiagent]

Hi @davidahmann, Thank you for your contribution! We appreciate you taking the time to submit this pull request. Your PR has been received by the team and is currently under review. We will provide feedback as soon as we have an update to share.

[ryanaiagent]

Hi @Jacksunwei , can you please review this. LGTM