chore: add tests for enums for required fields

[Noroth]

This PR just adds some more tests to verify that also enums are supported in the selection set of required fields

Summary by CodeRabbit

Release Notes

• New Features

  • Added federation support for enumeration-based fields, enabling resolution of direct and nested enum data.

• Tests

  • Expanded test coverage for enumeration federation scenarios with new test cases validating field resolution.

• Chores

  • Added RPC endpoints and updated field mappings to support enumeration-based federation.

Checklist

• I have discussed my proposed changes in an issue and have received approval to proceed.
• I have followed the coding standards of the project.
• Tests or benchmarks have been added or updated.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR extends federation @requires support in the gRPC datasource to handle enum and nested enum fields. It adds new RPC methods, proto message definitions, GraphQL schema fields, test coverage, and mock service implementations for resolving enum-based Storage fields (kindSummary and categoryInfoSummary).

Changes

Cohort / File(s)	Summary
Proto and Service Definitions v2/pkg/grpctest/product.proto	Added two new RPC endpoints (RequireStorageKindSummaryById, RequireStorageCategoryInfoSummaryById) and supporting message types (Context, Request, Response, Result, Fields) for enum and nested enum require resolution.
GraphQL Schema v2/pkg/grpctest/testdata/products.graphqls	Added StorageCategoryInfo type and four new Storage fields: storageKind, categoryInfo (marked @external), and kindSummary, categoryInfoSummary (marked @requires with corresponding field selections).
Configuration and Mappings v2/pkg/engine/datasource/grpc_datasource/mapping_test_helper.go, v2/pkg/grpctest/mapping/mapping.go	Extended Storage entity field mappings with storageKind, categoryInfo, kindSummary, and categoryInfoSummary, along with corresponding RPC and response configurations for the new require fields.
Mock Service Implementation v2/pkg/grpctest/mockservice_requires.go	Implemented two new server methods (RequireStorageKindSummaryById, RequireStorageCategoryInfoSummaryById) that extract nested fields and format summary strings; added fmt import.
Test Coverage v2/pkg/engine/datasource/grpc_datasource/execution_plan_requires_test.go, v2/pkg/engine/datasource/grpc_datasource/grpc_datasource_federation_test.go	Added comprehensive test cases verifying execution plans and federation behavior for enum and nested enum require fields, including GraphQL queries, field configurations, RPC plan assertions, and result validations.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• feat: add initial support for @requires in gRPC #1362: Adds @requires support for enum and nested enum fields in gRPC datasource federation, with overlapping proto definitions, RPC mappings, test cases, and execution plan verifications.

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'chore: add tests for enums for required fields' accurately describes the primary change: adding test coverage for enum support in required field selections across multiple test files.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch ludwig/eng-9155-ensure-enum-support-for-the-required-fields-selection

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