iam: add conformance tests for IAM Identity Management APIs for GCP

[SriramGuduri]

Summary

GCP IAM Admin API Conformance Testing Strategy

Specific challenges encountered with the GCP IAM Admin Java Client that necessitated a different testing approach compared to the standard REST-based conformance tests.

1. Client Transport Limitations (gRPC vs. REST)

Unlike other GCP client libraries we use, the google-iam-admin library does not natively expose an HTTP/JSON (REST) transport option in its StubSettings. It forces the use of gRPC, which requires HTTP/2. This prevented us from using our standard HTTP-based WireMock recording setup.

2. WireMock gRPC Extension Limitations

While we utilized the wiremock-grpc-extension to handle the HTTP/2 connection and protocol framing, it currently lacks full parity with the standard WireMock HTTP recorder:

• No Auto-Recording: The extension cannot transparently proxy binary gRPC streams and serialize the Protobuf responses into readable JSON files automatically.
• Strict Matching: The extension requires precise endpoint matching (e.g., strict leading slashes), which caused UNIMPLEMENTED errors when using standard auto-loaded mappings.

3. Implementation of Custom Record/Replay Pattern

To bridge this gap, we implemented a manual Record/Replay workflow:

• Record Mode:
  • Bypassed WireMock to connect directly to GCP.
  • Intercepted the response objects.
  • Manually serialized the Protobuf messages to JSON using JsonFormat and saved them to a dedicated recorded_responses directory (avoiding conflicts with WireMock's auto-scanner).
• Replay Mode:
  • Configured the client with SSL/ALPN to negotiate HTTP/2 with WireMock.
  • Programmatically loaded the JSON files, parsed them back into Protobuf objects, and registered them as stubs using the gRPC Extension DSL.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.67%. Comparing base (b5d5ab5) to head (741577f).

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #186      +/-   ##
============================================
+ Coverage     83.64%   83.67%   +0.02%     
- Complexity       90       91       +1     
============================================
  Files           150      150              
  Lines          8073     8073              
  Branches        941      941              
============================================
+ Hits           6753     6755       +2     
+ Misses          876      875       -1     
+ Partials        444      443       -1     

Flag	Coverage Δ
unittests	83.67% <ø> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.