ben-manes Assume the existing tests miss at least one real defect.
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
For each edge case, trace the code path. Does the code handle it correctly?
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)
For each candidate gap, provide a minimal test case with the specific cache configuration and thread interleaving needed to reach the code path.
Priority ordering:
- Paths involving the catch-commit-rethrow pattern (doComputeIfAbsent, remap)
- Slow paths reachable only via contention (synchronized blocks after optimistic checks)
- Interactions between expiration and the async value lifecycle (ASYNC_EXPIRY, isComputingAsync)
Focus only on behavioral coverage gaps that could hide correctness bugs.