switch with_connection to be sync with now_or_never

[insipx]

this is mostly a QoL pr since i noticed the wasm ephemeral db builds completely synchronously. this makes using some test utils more flexible, like making it possible to use proptest for db queries (not used yet)

[insipx]

This PR is part of a stack of 1 bookmark:

1. trunk()
2. insipx/sync-conn ← this PR

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Created with jj-stack

[claude]

Claude finished @insipx's task —— View job

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Code Review Complete

Review Date: November 25, 2025, 21:04 UTC

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Summary

This PR successfully converts the with_connection test harness from async to synchronous execution using FutureExt::now_or_never. The change is well-motivated and safe for the specific use case.

Positive Observations

1. Correct Usage of now_or_never: The implementation is safe because:

   • For Wasm ephemeral databases, WasmDb::new(&StorageOption::Ephemeral) creates an in-memory connection synchronously (see xmtp_db/src/encrypted_store/database/wasm.rs:123)
   • No await points exist in the ephemeral path - it calls WasmDbConnection::new_ephemeral() which immediately constructs a connection
   • The now_or_never() usage in xmtp_db/src/test_utils.rs:119 is therefore guaranteed to resolve immediately

2. Improved Test Ergonomics: The synchronous with_connection enables more flexible test patterns, including proptest usage as mentioned in the PR description

3. Consistent Pattern: All 22 test files have been updated consistently to remove .await calls, making the tests simpler

4. Preserved Async Path: The with_connection_async function is retained for tests that genuinely need async behavior

Concerns & Recommendations

1. Missing Test Coverage (82% patch coverage)

The codecov report shows 45 lines missing coverage, particularly in:

• xmtp_proto/src/types/cursor_list.rs (17 lines - 0% coverage)
• xmtp_db/src/encrypted_store/group_intent/types.rs (12 lines - 42.85% coverage)
• xmtp_db/src/encrypted_store/group_intent/error.rs (5 lines - 0% coverage)

Recommendation: These appear to be new utility types/errors introduced as part of the refactor. Consider adding tests for the uncovered code paths or document why they're acceptable to leave untested.

2. Potential Footgun for Future Developers

The synchronous with_connection looks like it should work for any database type, but it's actually only safe for ephemeral databases. If someone tries to use it with persistent storage, they'll get a panic at runtime.

Recommendation: Add a comment to xmtp_db/src/test_utils.rs:111 documenting this constraint:

/// Test harness that loads an Ephemeral store.
/// IMPORTANT: Only works with ephemeral databases because persistent databases
/// require async initialization (OPFS setup). Use `with_connection_async` for
/// persistent database tests.
pub fn with_connection<F, R>(fun: F) -> R

3. Dependency Management

The futures crate is added as an optional test-utils dependency (Cargo.toml:47, 98), but it's not clear if this is only for now_or_never or if there are other uses.

Recommendation: Since futures::FutureExt::now_or_never is a small utility, consider whether pulling in the entire futures crate is necessary. However, given that futures is likely already in the dependency tree, this is minor.

Code Quality

• ✅ Tests are correctly converted from async to sync
• ✅ No unnecessary changes beyond the stated goal
• ✅ Follows existing code patterns
• ✅ The PR reduces complexity (net -270 lines)

Verdict

Approve with minor suggestions. The core change is sound and well-executed. The main concerns are documentation and test coverage, which are low-priority improvements.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.19%. Comparing base (0b5a6fb) to head (0c9c8d2).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2820      +/-   ##
==========================================
- Coverage   74.65%   74.19%   -0.47%     
==========================================
  Files         387      387              
  Lines       50048    49262     -786     
==========================================
- Hits        37362    36548     -814     
- Misses      12686    12714      +28     

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[macroscopeapp]

Make xmtp_db::test_utils::with_connection synchronous and align Wasm initialization with FutureExt::now_or_never() in test_utils.rs

Convert the test harness and all affected tests to call a synchronous with_connection, removing await usage across the suite and adding futures to enable WasmDb::new(...).now_or_never() in Wasm builds.

📍Where to Start

Start with the with_connection helpers in test_utils.rs, then scan call sites in test modules to confirm synchronous usage and removal of .await.

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Macroscope summarized 0c9c8d2.