📜 Description

Adds 22 unit tests for CircularFifoQueue, a circular buffer data structure used internally (e.g., for breadcrumb storage) that previously had zero test coverage.

Tests cover:

• Construction: sized, default (32), from-collection, invalid size rejection (zero, negative)
• Core queue operations: add, peek, poll, remove, element, offer
• Overflow/eviction: oldest element evicted when capacity exceeded
• Wrap-around correctness: get(index) and iterator() return correct logical order after the internal ring buffer wraps
• Capacity queries: isAtFullCapacity (true when full), isFull (always false by design — the queue evicts rather than rejecting)
• Edge cases: empty queue (peek→null, poll→null, remove→throws, element→throws), clear reset, out-of-bounds get
• Multi-cycle correctness: interleaved add/remove sequences

💡 Motivation and Context

CircularFifoQueue is a 423-line data structure with non-trivial ring-buffer logic (modular indexing, wrap-around eviction, iterator over a potentially wrapped array). Despite this complexity, it had no dedicated tests. This is a test-only change — no production code was modified.

💚 How did you test it?

./gradlew :sentry:test --tests "*CircularFifoQueueTest*"
# All 22 tests PASSED

./gradlew :sentry:spotlessApply
# Formatting clean, no changes needed

Reviewer checklist

• Verify isFull always returns false matches the intended contract of CircularFifoQueue (it evicts rather than blocking/rejecting, so isFull is documented to always return false).
• Verify constructor from collection copies elements — confirm that CircularFifoQueue(collection) sets maxSize = collection.size.
• Spot-check wrap-around assertions (lines ~200–217): after adding "a","b","c","d" to a size-3 queue, get(0) should return "b" (oldest surviving element).
• Note: null-rejection test was omitted because Kotlin's type system prevents passing null to the @NotNull-annotated add() at compile time. The null guard is only exercisable from Java callers.

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

• Add thread-safety / concurrent-access tests if CircularFifoQueue is used across threads.
• Add a Java-side test to exercise the @NotNull null-rejection path.
• Other zero-coverage candidates in sentry core: DsnUtil, DiscardReason, ErrorUtils, ClassLoaderUtils.

Link to Devin session: https://app.devin.ai/sessions/23aaff7eb99e45c79503152f36003ab8
Requested by: @aks4396