Google-cloud-dotnet: Spanner Emulator, CallInvoker is set, contrary to use of EmulatorDetection.EmulatorOnly

[AliSheikhTaheri]

Hi

I would like to use Spanner Emulator for integration tests but when I use it with C# I get CallInvoker is set error.
The below is step by step to produce the error also I am attaching the simple code I have written in C#.

```
// for some reason C# doesn't find the environment variable so setting it manually
Environment.SetEnvironmentVariable("SPANNER_EMULATOR_HOST", "localhost:9010");

        string projectId = "project-local-emulator";
        string instanceId = "test-instance";

        var builder = new SpannerConnectionStringBuilder
        {
            DataSource = $"projects/{projectId}/instances/{instanceId}",
            EmulatorDetection = EmulatorDetection.EmulatorOnly,
        };

        await using var connection = new SpannerConnection(builder);

        string createStatement = $"CREATE DATABASE `test-db`";
        var cmdcreate = connection.CreateDdlCommand(createStatement);
        await cmdcreate.ExecuteNonQueryAsync();

```

Environment details

• OS: Mac OSX
• .NET Core 3.1

Steps to reproduce

1. Followed the instruction on this page: https://cloud.google.com/spanner/docs/emulator
2. Created an instance and a database
3. Trying to connect to the spanner emulator via C# and I am getting the following error

System.InvalidOperationException: CallInvoker is set, contrary to use of EmulatorDetection.EmulatorOnly

System.InvalidOperationException
CallInvoker is set, contrary to use of EmulatorDetection.EmulatorOnly
at Google.Api.Gax.GaxPreconditions.CheckStateT1,T2,T3
at Google.Api.Gax.Grpc.ClientBuilderBase1.GetEmulatorEnvironment(IEnumerable1 requiredEmulatorEnvironmentVariables, IEnumerable1 allEmulatorEnvironmentVariables, Func2 environmentVariableProvider)
at Google.Cloud.Spanner.Admin.Database.V1.DatabaseAdminClientBuilder.MaybeCreateEmulatorClientBuilder()
at Google.Cloud.Spanner.Admin.Database.V1.DatabaseAdminClientBuilder.InterceptBuild(DatabaseAdminClient& client)
at Google.Cloud.Spanner.Admin.Database.V1.DatabaseAdminClientBuilder.Build()
at Google.Cloud.Spanner.Data.SpannerCommand.ExecutableCommand.ExecuteDdlAsync(CancellationToken cancellationToken)
at Google.Cloud.Spanner.Data.SpannerCommand.ExecutableCommand.ExecuteDdlAsync(CancellationToken cancellationToken)

Would appreciate your help, as the error above doesn't really tell much what is wrong!

[jskeet]

Hmmm... that's definitely not what I'd expect. Will try to look into it this afternoon, but it may be Monday before I can get to it.

[jskeet]

Okay, I've reproduced it with this code:

using Google.Api.Gax;
using Google.Cloud.Spanner.Data;
using System;

namespace Issue5362
{
    class Program
    {
        static void Main(string[] args)
        {
            Environment.SetEnvironmentVariable("SPANNER_EMULATOR_HOST", "localhost:9010");
            var builder = new SpannerConnectionStringBuilder
            {
                DataSource = $"projects/xyz/instances/abc",
                EmulatorDetection = EmulatorDetection.EmulatorOnly,
            };
            using var connection = new SpannerConnection(builder);
            var command = connection.CreateDdlCommand("create database `test`");
            command.ExecuteNonQuery();
        }
    }
}

I've an idea what's wrong... will just need to validate.

[jskeet]

I've discovered the problem - it was simpler than I'd feared. We just need to get the change reviewed, and then I'll do another release. Unfortunately I can't think of a simple workaround for this in the meantime, other than performing the DDL manually with DatabaseAdminClient for the moment.

[jskeet]

This is now fixed in source code - I'll work with the Spanner team to schedule a new release with the fix in.

[jskeet]

This has now been released as part of the 3.3.0 set of libraries.

[AliSheikhTaheri]

Thank you so much Jon Skeet, you are legend! I will give this a go and let you know if there is any issue. 🙏