Feature | Fix enhanced routing ack handling.

[mdaigle]

Ports #3922 to main

[Copilot]

Pull request overview

This pull request fixes the handling of enhanced routing acknowledgment in SQL Server connections. The PR ensures that enhanced routing information (which includes a database name) is only used when the server explicitly acknowledges support for the FEATUREEXT_ENHANCEDROUTINGSUPPORT feature extension. If the server doesn't acknowledge the feature or explicitly disables it, the routing information is ignored and the connection stays with the current server.

Changes:

• Added validation logic to ignore enhanced routing info when DatabaseName is present but IsEnhancedRoutingSupportEnabled is false
• Updated OnFeatureExtAck to process enhanced routing feature acknowledgment even during routing
• Refactored unit tests to use a helper class pattern and cover both sync and async code paths

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/Connection/SqlConnectionInternal.cs	Added enhanced routing acknowledgment validation in LoginNoFailover and LoginWithFailover methods; updated OnFeatureExtAck to allow processing of enhanced routing feature
src/Microsoft.Data.SqlClient/tests/UnitTests/SimulatedServerTests/ConnectionEnhancedRoutingTests.cs	Refactored tests to use TestRoutingServers helper class; converted to Theory-based tests covering sync/async paths and multiple server behaviors

[Copilot]

The use of continue here is inconsistent with the equivalent logic in LoginNoFailover (line 3299), which uses break. Both are functionally equivalent since RoutingInfo is set to null immediately before, but break is more explicit and clearer about the intent to exit the routing loop. Consider changing continue to break for consistency.

Suggested change

	continue;
	break;