Updates Dart test template to use the first enum value for string properties with enums when generating test data, instead of always using the example value. This ensures generated test data is valid for properties with restricted enum values.

What does this PR do?

This PR updates the Dart SDK test generation template (service_test.dart.twig) to properly handle enum properties in generated test mocks. Previously, all string properties used property.example as mock values, which could lead to invalid enum values causing "Bad state: No element" errors in model constructors like Message.fromMap when the example value didn't match any enum option.

The change adds conditional logic for string properties:

• If the property has an enum defined, use the first enum value (property.enum[0]) as the mock value
• Otherwise, fall back to using property.example as before

This ensures that generated tests use valid enum values for properties with enums, preventing runtime errors during test execution.

Test Plan

regenerate sdk and run dart test

also push changes and ensure the GitHub Actions workflow for Dart SDK completes successfully with all tests passing. #1247

before:


after:

Have you read the Contributing Guidelines on issues?

Yes

Summary by CodeRabbit

• New Features

  • Test data generation now prefers the first enum value for string properties when available, falling back to examples otherwise.

• Tests

  • Response assertions adjusted: multi-model responses are validated as maps; single-model responses still expect specific types.
  • Account channel test now asserts a specific channel string rather than a wildcard.

• Chores

  • No public API changes.

_{✏️ Tip: You can customize this high-level summary in your review settings.}