Add HotChocolate server in-memory provider to Fusion

src/All.slnx

@@ -215,6 +215,7 @@
     <Project Path="HotChocolate/Fusion/src/Fusion.Composition/HotChocolate.Fusion.Composition.csproj" />
     <Project Path="HotChocolate/Fusion/src/Fusion.Diagnostics/HotChocolate.Fusion.Diagnostics.csproj" />
     <Project Path="HotChocolate/Fusion/src/Fusion.Execution.Types/HotChocolate.Fusion.Execution.Types.csproj" />
+    <Project Path="HotChocolate/Fusion/src/Fusion.Connectors.InMemory/HotChocolate.Fusion.Connectors.InMemory.csproj" />
     <Project Path="HotChocolate/Fusion/src/Fusion.Execution/HotChocolate.Fusion.Execution.csproj" />
     <Project Path="HotChocolate/Fusion/src/Fusion.Language/HotChocolate.Fusion.Language.csproj" />
     <Project Path="HotChocolate/Fusion/src/Fusion.Packaging/HotChocolate.Fusion.Packaging.csproj" />
@@ -224,6 +225,7 @@
   <Folder Name="/HotChocolate/Fusion/test/">
     <Project Path="HotChocolate/Fusion/test/Fusion.AspNetCore.Tests/HotChocolate.Fusion.AspNetCore.Tests.csproj" />
     <Project Path="HotChocolate/Fusion/test/Fusion.Composition.Tests/HotChocolate.Fusion.Composition.Tests.csproj" />
+    <Project Path="HotChocolate/Fusion/test/Fusion.Connectors.InMemory.Tests/HotChocolate.Fusion.Connectors.InMemory.Tests.csproj" />
     <Project Path="HotChocolate/Fusion/test/Fusion.Diagnostics.Tests/HotChocolate.Fusion.Diagnostics.Tests.csproj" />
     <Project Path="HotChocolate/Fusion/test/Fusion.EventSources.Tests/HotChocolate.Fusion.EventSources.Tests.csproj" />
     <Project Path="HotChocolate/Fusion/test/Fusion.Execution.Tests/HotChocolate.Fusion.Execution.Tests.csproj" />

src/HotChocolate/Core/src/Execution.Abstractions/Execution/VariableBatchRequest.cs

@@ -205,4 +205,65 @@ public VariableBatchRequest WithFeatures(IFeatureCollection? features)
             features,
             Services,
             Flags);
+
+    /// <summary>
+    /// Creates a new <see cref="VariableBatchRequest"/> from a GraphQL source text
+    /// and a JSON array of variable sets.
+    /// </summary>
+    /// <param name="sourceText">
+    /// The GraphQL operation source text.
+    /// </param>
+    /// <param name="variableValues">
+    /// A JSON document whose root element is an array of variable objects.
+    /// </param>
+    /// <param name="documentHash">
+    /// A GraphQL request document hash.
+    /// </param>
+    /// <param name="operationName">
+    /// A name of an operation in the GraphQL request document that shall be executed.
+    /// </param>
+    /// <param name="errorHandlingMode">
+    /// The requested error handling mode.
+    /// </param>
+    /// <param name="extensions">
+    /// The GraphQL request extension data.
+    /// </param>
+    /// <param name="contextData">
+    /// The initial global request state.
+    /// </param>
+    /// <param name="features">
+    /// The features that shall be used while executing the GraphQL request.
+    /// </param>
+    /// <param name="services">
+    /// The services that shall be used while executing the GraphQL request.
+    /// </param>
+    /// <param name="flags">
+    /// The GraphQL request flags can be used to limit the execution engine capabilities.
+    /// </param>
+    /// <returns>
+    /// Returns a new variable batch request.
+    /// </returns>
+    public static VariableBatchRequest FromSourceText(
+        string sourceText,
+        JsonDocument variableValues,
+        OperationDocumentHash? documentHash = null,
+        string? operationName = null,
+        ErrorHandlingMode? errorHandlingMode = null,
+        JsonDocument? extensions = null,
+        IReadOnlyDictionary<string, object?>? contextData = null,
+        IFeatureCollection? features = null,
+        IServiceProvider? services = null,
+        RequestFlags flags = RequestFlags.AllowAll)
+        => new(
+            new OperationDocumentSourceText(sourceText),
+            null,
+            documentHash,
+            operationName,
+            errorHandlingMode,
+            new JsonDocumentOwner(variableValues),
+            extensions is null ? null : new(extensions),
+            contextData,
+            features,
+            services,
+            flags);
 }

src/HotChocolate/Fusion/HotChocolate.Fusion.slnx

@@ -12,6 +12,7 @@
     <Project Path="src/Fusion.Language/HotChocolate.Fusion.Language.csproj" />
     <Project Path="src/Fusion.Packaging/HotChocolate.Fusion.Packaging.csproj" />
     <Project Path="src/Fusion.SourceSchema.Packaging/HotChocolate.Fusion.SourceSchema.Packaging.csproj" />
+    <Project Path="src/Fusion.Connectors.InMemory/HotChocolate.Fusion.Connectors.InMemory.csproj" />
     <Project Path="src/Fusion.Utilities/HotChocolate.Fusion.Utilities.csproj" />
   </Folder>
   <Folder Name="/test/">
@@ -23,6 +24,7 @@
     <Project Path="test/Fusion.Language.Tests/HotChocolate.Fusion.Language.Tests.csproj" />
     <Project Path="test/Fusion.Packaging.Tests/HotChocolate.Fusion.Packaging.Tests.csproj" />
     <Project Path="test/Fusion.SourceSchema.Packaging.Tests/HotChocolate.Fusion.SourceSchema.Packaging.Tests.csproj" />
+    <Project Path="test/Fusion.Connectors.InMemory.Tests/HotChocolate.Fusion.Connectors.InMemory.Tests.csproj" />
     <Project Path="test/Fusion.Utilities.Tests/HotChocolate.Fusion.Utilities.Tests.csproj" />
     <Project Path="test/Fusion.Tests.Shared/HotChocolate.Fusion.Tests.Shared.csproj" />
   </Folder>

src/HotChocolate/Fusion/src/Fusion.Composition/SchemaCompositionException.cs

@@ -0,0 +1,47 @@
+using HotChocolate.Fusion.Logging;
+
+namespace HotChocolate.Fusion.Composition;
+
+/// <summary>
+/// The exception that is thrown when schema composition fails.
+/// </summary>
+public sealed class SchemaCompositionException : Exception
+{
+    /// <summary>
+    /// Initializes a new instance of <see cref="SchemaCompositionException"/>.
+    /// </summary>
+    /// <param name="compositionLog">The composition log containing the errors.</param>
+    public SchemaCompositionException(CompositionLog compositionLog)
+        : base(BuildMessage(compositionLog))
+    {
+        CompositionLog = compositionLog;
+    }
+
+    /// <summary>
+    /// Gets the composition log containing the detailed errors and warnings
+    /// encountered during schema composition.
+    /// </summary>
+    public CompositionLog CompositionLog { get; }
+
+    private static string BuildMessage(CompositionLog log)
+    {
+        ArgumentNullException.ThrowIfNull(log);
+
+        var messages = new List<string>();
+
+        foreach (var entry in log)
+        {
+            if (entry.Severity == LogSeverity.Error)
+            {
+                messages.Add(entry.Message);
+            }
+        }
+
+        return messages.Count switch
+        {
+            0 => "Schema composition failed.",
+            1 => $"Schema composition failed: {messages[0]}",
+            _ => $"Schema composition failed with {messages.Count} errors: {messages[0]}"
+        };
+    }
+}

src/HotChocolate/Fusion/src/Fusion.Connectors.InMemory/DependencyInjection/InMemoryFusionGatewayBuilderExtensions.cs

@@ -0,0 +1,93 @@
+using HotChocolate.Execution;
+using HotChocolate.Execution.Configuration;
+using HotChocolate.Fusion.Configuration;
+using HotChocolate.Fusion.Connectors.InMemory;
+using HotChocolate.Fusion.Execution.Clients;
+using HotChocolate.Transport.Formatters;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+/// <summary>
+/// Extension methods for registering the in-memory connector on <see cref="IFusionGatewayBuilder"/>.
+/// </summary>
+public static class InMemoryFusionGatewayBuilderExtensions
+{
+    /// <summary>
+    /// Adds an in-memory schema connector that executes operations directly in-process
+    /// against the schema registered by the given <paramref name="schemaBuilder"/>.
+    /// </summary>
+    /// <param name="builder">The fusion gateway builder.</param>
+    /// <param name="schemaBuilder">
+    /// The request executor builder whose <see cref="IRequestExecutorBuilder.Name"/>
+    /// identifies the source schema.
+    /// </param>
+    /// <returns>The fusion gateway builder for chaining.</returns>
+    public static IFusionGatewayBuilder AddInMemorySchema(
+        this IFusionGatewayBuilder builder,
+        IRequestExecutorBuilder schemaBuilder)
+    {
+        ArgumentNullException.ThrowIfNull(schemaBuilder);
+
+        return builder.AddInMemorySchema(schemaBuilder.Name);
+    }
+
+    /// <summary>
+    /// Adds an in-memory schema connector that executes operations directly in-process
+    /// against the schema identified by <paramref name="schemaName"/>.
+    /// </summary>
+    /// <param name="builder">The fusion gateway builder.</param>
+    /// <param name="schemaName">The name of the source schema.</param>
+    /// <returns>The fusion gateway builder for chaining.</returns>
+    public static IFusionGatewayBuilder AddInMemorySchema(
+        this IFusionGatewayBuilder builder,
+        string schemaName)
+    {
+        ArgumentNullException.ThrowIfNull(builder);
+        ArgumentException.ThrowIfNullOrEmpty(schemaName);
+
+        if (!builder.Services.Any(d => d.ServiceType == typeof(InMemorySourceSchemaClientFactory)))
+        {
+            // Remove default HTTP client factory — in-memory mode doesn't need it.
+            for (var i = builder.Services.Count - 1; i >= 0; i--)
+            {
+                if (builder.Services[i].ServiceType == typeof(ISourceSchemaClientFactory))
+                {
+                    builder.Services.RemoveAt(i);
+                }
+            }
+
+            builder.Services.AddSingleton(
+                static sp => new InMemorySourceSchemaClientFactory(
+                    sp.GetRequiredService<IRequestExecutorProvider>(),
+                    sp.GetRequiredService<IRequestExecutorEvents>(),
+                    JsonResultFormatter.Default));
+
+            builder.Services.AddSingleton<ISourceSchemaClientFactory>(
+                static sp => sp.GetRequiredService<InMemorySourceSchemaClientFactory>());
+        }
+
+        builder.Services.AddSingleton(new InMemorySchemaRegistration(schemaName));
+
+        FusionSetupUtilities.Configure(
+            builder,
+            setup => setup.DocumentProvider = sp =>
+            {
+                var names = sp.GetServices<InMemorySchemaRegistration>()
+                    .Select(r => r.SchemaName).ToArray();
+                return new InMemoryConfigurationProvider(
+                    names,
+                    sp.GetRequiredService<IRequestExecutorProvider>(),
+                    sp.GetRequiredService<IRequestExecutorEvents>());
+            });
+
+        FusionSetupUtilities.Configure(
+            builder,
+            setup => setup.ClientConfigurationModifiers.Add(
+                _ => new InMemorySourceSchemaClientConfiguration(schemaName)));
+
+        return builder;
+    }
+}
+
+internal sealed record InMemorySchemaRegistration(string SchemaName);

src/HotChocolate/Fusion/src/Fusion.Connectors.InMemory/HotChocolate.Fusion.Connectors.InMemory.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <AssemblyName>HotChocolate.Fusion.Connectors.InMemory</AssemblyName>
+    <RootNamespace>HotChocolate.Fusion</RootNamespace>
+    <LangVersion>preview</LangVersion>
+    <DefineConstants>$(DefineConstants);FUSION</DefineConstants>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <InternalsVisibleTo Include="HotChocolate.Fusion.Connectors.InMemory.Tests" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\Core\src\Core\HotChocolate.Core.csproj" />
+    <ProjectReference Include="..\..\..\AspNetCore\src\Transport.Formatters\HotChocolate.Transport.Formatters.csproj" />
+    <ProjectReference Include="..\Fusion.Composition\HotChocolate.Fusion.Composition.csproj" />
+    <ProjectReference Include="..\Fusion.Execution\HotChocolate.Fusion.Execution.csproj" />
+  </ItemGroup>
+
+</Project>