chore: add more tests + small improvements for .NET wrapper #689

olavloite · 2025-12-10T09:59:47Z

Adds some more tests for the .NET wrapper and fixes some issues with multi-statement SQL strings that return errors for the second (or later) statement.

This change also removes the option to use unary RPCs to fetch results using the gRPC API in the .NET wrapper, as the performance of that is slower than using a streaming RPC. This will in a future pull request be replaced with a protocol that uses a bi-directional gRPC stream.

Adds some more tests for the .NET wrapper and fixes some issues with multi-statement SQL strings that return errors for the second (or later) statement. This change also removes the option to use unary RPCs to fetch results using the gRPC API in the .NET wrapper, as the performance of that is slower than using a streaming RPC. This will in a future pull request be replaced with a protocol that uses a bi-directional gRPC stream.

gemini-code-assist · 2025-12-10T10:00:20Z

Summary of Changes

Hello @olavloite, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves the robustness and test coverage of the .NET wrapper for SpannerLib. Key changes include fixing issues related to multi-statement SQL execution, optimizing result fetching by exclusively using streaming gRPC RPCs, and adding comprehensive tests for various scenarios, including partial result consumption and error handling within multi-statement queries. These updates ensure a more reliable and performant client experience.

Highlights

Enhanced .NET Wrapper Testing: Added new and improved tests, including scenarios for multi-statement SQL execution, partial result set consumption, and error handling.
Multi-Statement SQL Fixes: Resolved issues where multi-statement SQL strings could return errors on subsequent statements, ensuring robust execution.
Unary RPC Removal for Results: Eliminated the option to use unary RPCs for fetching query results in the .NET wrapper, standardizing on the more performant streaming RPCs.
Internal Refactoring for Streaming: The Go gRPC server-side ExecuteStreaming logic was refactored into a dedicated streamRows function to better handle result set streaming and error propagation.
Improved StreamingRows Behavior: The StreamingRows implementation in the .NET wrapper now correctly handles Next() and NextResultSet() calls after a result set has been exhausted, and properly clears metadata for subsequent result sets.
Mock Server Enhancements: The mock server gained new capabilities, including generating result sets with nullable values and a new CreateSelect2ResultSet helper.

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Code Review

This pull request refactors the ExecuteStreaming logic in spannerlib/grpc-server/server.go into a new streamRows helper function, improving error handling for NextResultSet and moving the CloseRows defer statement. In the C# wrapper (spannerlib-dotnet-grpc-impl/GrpcLibSpanner.cs), the GrpcLibSpanner class is made sealed, client-side load balancing is introduced by managing multiple gRPC channels and clients, and all API calls are updated to use a randomly selected client. The _useStreamingRows flag is removed, making streaming the default execution path, and helper methods are made private. The StreamingRows.cs file receives a license header, and its NextResultSet methods are updated to pre-fetch the next row and clear metadata. The mock server (spannerlib-dotnet-mockserver/MockSpannerServer.cs) gains new helper methods for creating specific result sets, and RandomResultSetGenerator.cs is enhanced to optionally generate null values and correctly format Int64 values as strings. Test files (BasicTests.cs, RowsTests.cs) are updated to enable previously ignored async tests, parameterize existing tests, and add new tests for handling multiple queries, stopping row consumption midway, and error scenarios during mixed statement execution. Review comments highlight that the use of Random.Shared in RandomResultSetGenerator.cs and RowsTests.cs for generating test data and scenarios makes tests non-deterministic, recommending refactoring for deterministic and reliable test execution.

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-tests/RowsTests.cs

olavloite · 2025-12-10T10:22:58Z

spannerlib/grpc-server/server.go

+	return s.streamRows(queryContext, rows, stream)
+}
+
+func (s *spannerLibServer) streamRows(queryContext context.Context, rows *pb.Rows, stream grpc.ServerStreamingServer[pb.RowData]) error {


Moving this logic into a separate function makes it easier to re-use. It will be re-used in the bi-directional gRPC stream implementation in a follow-up PR.

olavloite · 2025-12-10T10:24:11Z

spannerlib/grpc-server/server.go

 				if err := stream.Send(res); err != nil {
 					return err
 				}
+				if nextResultSetErr != nil {


This ensures that calling NextResultSet when using the streaming gRPC API returns an error if the second (or third, ...) SQL statement in a multi-statement SQL string fails.

olavloite · 2025-12-10T10:24:49Z

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-grpc-impl/GrpcLibSpanner.cs

-    private readonly V1.SpannerLib.SpannerLibClient _client;
-    private readonly GrpcChannel _channel;


Replaced this with an implementation that always uses a (very simple) channel pool.

olavloite · 2025-12-10T10:25:26Z

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-grpc-impl/GrpcLibSpanner.cs

-    private readonly GrpcChannel _channel;
    private readonly V1.SpannerLib.SpannerLibClient[] _clients;
    private readonly GrpcChannel[] _channels;
-    private readonly bool _useStreamingRows;


Removed this option, as there is no good reason why we would not use the streaming implementation.

olavloite · 2025-12-10T10:26:04Z

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-grpc-impl/GrpcLibSpanner.cs

    public Pool CreatePool(string connectionString)
    {
-        return FromProto(TranslateException(() => _client.CreatePool(new CreatePoolRequest
+        return FromProto(TranslateException(() => Client.CreatePool(new CreatePoolRequest


This picks a channel from the 'pool' instead of always just using one fixed channel.

olavloite · 2025-12-10T10:26:45Z

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-grpc-impl/StreamingRows.cs


-        return HasNextResultSet();
+        var hasNextResultSet = HasNextResultSet();
+        _pendingRow = Next();


This call is needed to ensure that the error is propagated to the application if the second (or third, ...) statement in a multi-statement SQL string failed.

bhatt4982

LGTM...

olavloite requested a review from a team as a code owner December 10, 2025 09:59

gemini-code-assist bot reviewed Dec 10, 2025

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spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-tests/RowsTests.cs Show resolved Hide resolved

spannerlib/wrappers/spannerlib-dotnet/spannerlib-dotnet-tests/RowsTests.cs Show resolved Hide resolved

olavloite requested a review from bhatt4982 December 10, 2025 10:21

olavloite commented Dec 10, 2025

View reviewed changes

bhatt4982 approved these changes Dec 10, 2025

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olavloite merged commit 525709c into main Dec 11, 2025
46 of 49 checks passed

olavloite deleted the spanner-lib-improve-dotnet-tests branch December 11, 2025 08:03

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chore: add more tests + small improvements for .NET wrapper #689

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		private readonly V1.SpannerLib.SpannerLibClient _client;
		private readonly GrpcChannel _channel;

chore: add more tests + small improvements for .NET wrapper #689

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