The tests in FilterDocumentsTest validate filter logic correctness (operations, error, edge cases) That logic lives in the filter translation layer, which is the same code regardless of whether it's called sync or async.

The async path only differs in how the query is issued. If that works for one filter, it works for all of them.

A small FilterDocumentsAsyncTest with 3 smoke tests:

• test_no_filters_async: Verifies the async path returns all docs with no filter
• test_filter_simple_async: One equality filter — confirms async plumbing works with a filter
• test_filter_compound_async: One AND filter — verifies compound filters aren't broken by the async path