Audit Coverage Gaps

Assume the existing tests miss at least one real defect.

1. For each public method, identify the hardest-to-test edge cases:

   • Null values (where permitted)
   • Maximum/minimum weight
   • Zero-duration expiration
   • Mapping functions that return the same instance
   • Mapping functions that throw
   • Weighers that throw
   • Expiry callbacks that throw
   • CompletableFuture values (async cache edge cases)
   • Keys/values with adversarial hashCode/equals

2. For each edge case, trace the code path. Does the code handle it correctly?

3. Identify combinatorially hard behavioral dimensions:

   • Operation A on expired entry during concurrent operation B
   • Exception in user callback X while holding lock Y
   • GC collecting reference R between code points P and Q
   • Fast path falls through to slow path under contention (e.g., entry appears expired on fast path, recovers under lock on slow path)
   • Async cache: future completes between check and action (e.g., isComputingAsync returns true, but future completes before the code that depends on that check executes)

4. For each candidate gap, provide a minimal test case with the specific cache configuration and thread interleaving needed to reach the code path.