test(storage): serialize transport tracing tests to fix flaky test

[vsharonlynn]

Fixes #6324 .

[gemini-code-assist]

Code Review

This pull request updates the integration tests in src/storage/src/storage/transport.rs to run serially by adding the #[serial] attribute from the serial_test crate. This change allows several previously ignored flaky tests, such as open_object_success, open_appendable_object_success, and open_appendable_object_finalize_success, to be re-enabled. I have no feedback to provide.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.65%. Comparing base (102298f) to head (b21ebaf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6520      +/-   ##
==========================================
+ Coverage   96.39%   96.65%   +0.25%     
==========================================
  Files         301      301              
  Lines       84762    84751      -11     
==========================================
+ Hits        81706    81914     +208     
+ Misses       3056     2837     -219     

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[joshuatants]

Out of curiosity, why did allowing the tests to run in parallel cause flakiness?

[coryan]

Out of curiosity, why did allowing the tests to run in parallel cause flakiness?

Because only one test can set the global tracing dispatcher at a time. However, this is unlikely to work. This is serializing all the tests in this module, but cargo runs the tests in the crate in parallel. Any other test setting the global will break you.

There is a way to set the dispatcher for the current task, but that has failed us elsewhere.

We are finding that all these tracing tests are flaky across the board. We may need to move to cargo nextest for CI. In the interim, I think it is safer to leave them disabled.