test(foundation): add comprehensive unit tests for Memory storage implementations

[ashum9]

Summary

Adds comprehensive unit tests for FileBasedStorage — the disk-backed persistent memory implementation in mofa-foundation. This is the third PR in the incremental testing series for mofa-foundation's Memory component.

Part of the pre-GSoC testing series:

• PR test(foundation): add unit tests for InMemoryStorage basic operations #1220 — InMemoryStorage basic CRUD operations
• PR test(foundation): add examples and unit tests for InMemoryStorage search and history #1221 — InMemoryStorage search, history, and stats + runnable example
• PR test(foundation): add comprehensive unit tests for Memory storage implementations #1284 (this PR) — FileBasedStorage persistence, clear, and concurrency

What it does

1. test_file_based_persistence — Writes keys, history, long-term memory, and daily notes to disk in one FileBasedStorage scope, then re-opens the same directory in a new scope and verifies everything survived the drop (simulating an agent restart).

2. test_file_based_clear — Stores data and history, calls clear(), then asserts the in-memory maps are empty, data.json has been removed from disk, and the sessions/ directory exists but is empty.

3. test_file_based_concurrency — Spawns 10 concurrent Tokio tasks each acquiring a write lock (Arc<RwLock<FileBasedStorage>>), stores a unique key and appends a history message per task, then verifies all 10 values and 10 history entries are present after join.

Changes

• crates/mofa-foundation/src/agent/components/memory.rs — adds #[cfg(test)] mod tests block with the three async FileBasedStorage tests; imports (TempDir, Arc, RwLock) are placed at the top of the test module.

cc @amosli @BH3GEI

[Copilot]

Pull request overview

Adds unit tests to validate the behavior of mofa-foundation’s Memory storage implementations (in-memory and file-based), focusing on CRUD operations, history handling, and persistence semantics.

Changes:

• Add async unit tests for InMemoryStorage basic operations plus search/history behavior.
• Add file-based storage tests covering persistence across re-initialization, clearing behavior, and a concurrency scenario.
• Introduce temp-dir-backed test setup via tempfile.

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