test(showcase): add integration tests for retries

[nnicolee]

Description

This PR expands E2E retry integration tests verifying that client-side retry attempts adhere to configured retry settings and timeout limits across both gRPC and HTTP/JSON transports.

Key Changes

• SequenceService Client Configuration:
  • Uses client initializer methods in TestClientInitializer for creating SequenceServiceClient instances configured with custom retry parameters and disabled jitter.
• Expanded Test Coverage:
  • Exponential Backoff: Tests recovery across a standard error sequence (UNAVAILABLE -> UNAVAILABLE -> UNAVAILABLE -> OK).
  • No-Retry Config (maxAttempts = 1): Verifies that single-attempt settings abort immediately on the first error.
  • Non-Retryable Error: Verifies that non-retryable status codes (INVALID_ARGUMENT) halt retries immediately even when maxAttempts > 1.
  • Multiple Retryable Codes: Verifies retrying through a sequence of different retryable status codes (UNAVAILABLE -> RESOURCE_EXHAUSTED -> DEADLINE_EXCEEDED -> OK).
  • RPC Timeout Retries (rpcTimeout): Verifies that attempt timeouts cancel individual calls and trigger retries when server delay exceeds the attempt deadline.
  • Total Timeout Enforcement (totalTimeout): Verifies that cumulative operation deadlines terminate the retry loop with DEADLINE_EXCEEDED when total time expires.
• Flake-Free Verification:
  • Uses the mock server's stateful SequenceService report polled via Awaitility to verify attempt counts and status code sequences, removing local CPU context-switching scheduling lag as a source of test flakiness.

[gemini-code-assist]

Code Review

This pull request introduces integration tests for verifying exponential backoff retries on both gRPC and HTTP/JSON clients using the SequenceServiceClient. It also adds corresponding helper methods in TestClientInitializer to initialize these clients with custom retry settings. The feedback suggests simplifying the helper methods in TestClientInitializer by configuring SequenceServiceSettings.Builder directly, which avoids intermediate stub settings and unnecessary object allocations.

[nnicolee]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces integration tests for retry logic (ITRetries.java) across both gRPC and HTTP/JSON clients, covering scenarios such as exponential backoff, no retry, non-retryable errors, multiple status codes, and timeouts. It also adds helper methods in TestClientInitializer.java to initialize SequenceServiceClient instances with custom retry settings. The review feedback suggests improving code readability by removing redundant fully qualified class names (like com.google.rpc.Code and java.time.Duration) since these classes are already imported.

[nnicolee]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces integration tests for retry logic in ITRetries.java using both gRPC and HTTP/JSON clients, alongside helper methods in TestClientInitializer.java to initialize these clients with custom retry settings. The review feedback focuses on ensuring exception-safe resource management during client setup and teardown in the test class to prevent potential resource leaks, as well as removing redundant @SuppressWarnings("deprecation") annotations from the test methods.