[Fusion] Add FusionGatewayBuilder.UseRequest

src/HotChocolate/Fusion/src/Core/DependencyInjection/FusionRequestExecutorBuilderExtensions.cs

@@ -409,6 +409,88 @@
         return builder;
     }
 
+    /// <summary>
+    /// Adds a type that will be used to create a middleware for the execution pipeline.
+    /// </summary>
+    /// <param name="builder">
+    /// The gateway builder.
+    /// </param>
+    /// <returns>
+    /// Returns the gateway builder for configuration chaining.
+    /// </returns>
+    public static FusionGatewayBuilder UseRequest<TMiddleware>(
+        this FusionGatewayBuilder builder)
+        where TMiddleware : class
+    {
+        if (builder is null)
+        {
+            throw new ArgumentNullException(nameof(builder));
+        }
+
+        builder.CoreBuilder.UseRequest<TMiddleware>();
+        return builder;
+    }
+
+    /// <summary>
+    /// Adds a delegate that will be used to create a middleware for the execution pipeline.
+    /// </summary>
+    /// <param name="builder">
+    /// The gateway builder.
+    /// </param>
+    /// <param name="middleware">
+    /// A delegate that is used to create a middleware for the execution pipeline.
+    /// </param>
+    /// <returns>
+    /// Returns the gateway builder for configuration chaining.
+    /// </returns>
+    public static FusionGatewayBuilder UseRequest(
+        this FusionGatewayBuilder builder,
+        RequestCoreMiddleware middleware)
+    {
+        if (builder is null)
+        {
+            throw new ArgumentNullException(nameof(builder));
+        }
+
+        if (middleware is null)
+        {
+            throw new ArgumentNullException(nameof(middleware));
+        }
+
+        builder.CoreBuilder.UseRequest(middleware);
+        return builder;
+    }
+
+    /// <summary>
+    /// Adds a delegate that will be used to create a middleware for the execution pipeline.
+    /// </summary>
+    /// <param name="builder">
+    /// The gateway builder.
+    /// </param>
+    /// <param name="middleware">
+    /// A delegate that is used to create a middleware for the execution pipeline.
+    /// </param>
+    /// <returns>
+    /// Returns the gateway builder for configuration chaining.
+    /// </returns>
+    public static FusionGatewayBuilder UseRequest(
+        this FusionGatewayBuilder builder,
+        RequestMiddleware middleware)
+    {
+        if (builder is null)
+        {
+            throw new ArgumentNullException(nameof(builder));
+        }
+
+        if (middleware is null)
+        {
+            throw new ArgumentNullException(nameof(middleware));
+        }
+
+        builder.CoreBuilder.UseRequest(middleware);
+        return builder;
+    }
+
     private static IRequestExecutorBuilder UseFusionDefaultPipeline(
         this IRequestExecutorBuilder builder)
     {
@@ -481,7 +563,7 @@
             throw new ArgumentNullException(nameof(builder));
         }
 
-        return builder.UseRequest<DistributedOperationExecutionMiddleware>();
+        return builder.UseRequest(DistributedOperationExecutionMiddleware.Create());
     }
 
     internal static void AddDefaultPipeline(this IList<RequestCoreMiddleware> pipeline)

src/HotChocolate/Fusion/test/Core.Tests/RequestPipelineTests.cs

@@ -0,0 +1,158 @@
+using CookieCrumble;
+using HotChocolate.Execution;
+using HotChocolate.Fetching;
+using HotChocolate.Fusion.Composition;
+using HotChocolate.Fusion.Composition.Features;
+using HotChocolate.Fusion.Shared;
+using HotChocolate.Skimmed.Serialization;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit.Abstractions;
+using static HotChocolate.Language.Utf8GraphQLParser;
+
+namespace HotChocolate.Fusion;
+
+public class RequestPipelineTests(ITestOutputHelper output)
+{
+    private readonly Func<ICompositionLog> _logFactory = () => new TestCompositionLog(output);
+
+    [Fact]
+    public async Task Custom_Middleware_Runs_Before_DefaultPipeline()
+    {
+        // arrange
+        using var demoProject = await DemoProject.CreateAsync();
+
+        var fusionGraph =
+            await new FusionGraphComposer(logFactory: _logFactory)
+                .ComposeAsync(new[] { demoProject.Accounts.ToConfiguration() });
+
+        var config = new DemoIntegrationTests.HotReloadConfiguration(
+            new GatewayConfiguration(
+                SchemaFormatter.FormatAsDocument(fusionGraph)));
+
+        var executor = await new ServiceCollection()
+            .AddSingleton(demoProject.HttpClientFactory)
+            .AddFusionGatewayServer()
+            .RegisterGatewayConfiguration(_ => config)
+            .UseRequest<TestMiddleware>()
+            .UseDefaultPipeline()
+            .BuildRequestExecutorAsync();
+
+        // act
+        var result = await executor.ExecuteAsync(
+            OperationRequestBuilder.New()
+                .SetDocument("{ __typename }")
+                .AddGlobalState("short-circuit", true)
+                .Build());
+
+        // assert
+        result.MatchInlineSnapshot("""
+                                   {
+                                     "data": {
+                                       "result": true
+                                     },
+                                     "extensions": {
+                                       "state": "custom middleware short-circuited"
+                                     }
+                                   }
+                                   """);
+    }
+
+    [Fact]
+    public async Task Custom_Middleware_Falls_Through_To_DefaultPipeline()
+    {
+        // arrange
+        using var demoProject = await DemoProject.CreateAsync();
+
+        var fusionGraph =
+            await new FusionGraphComposer(logFactory: _logFactory)
+                .ComposeAsync(new[] { demoProject.Accounts.ToConfiguration() });
+
+        var config = new DemoIntegrationTests.HotReloadConfiguration(
+            new GatewayConfiguration(
+                SchemaFormatter.FormatAsDocument(fusionGraph)));
+
+        var executor = await new ServiceCollection()
+            .AddSingleton(demoProject.HttpClientFactory)
+            .AddFusionGatewayServer()
+            .RegisterGatewayConfiguration(_ => config)
+            .UseRequest<TestMiddleware>()
+            .UseDefaultPipeline()
+            .BuildRequestExecutorAsync();
+
+        // act
+        var result = await executor.ExecuteAsync("{ __typename }");
+
+        // assert
+        result.MatchInlineSnapshot("""
+                                   {
+                                     "data": {
+                                       "__typename": "Query"
+                                     }
+                                   }
+                                   """);
+    }
+
+    [Fact]
+    public async Task Custom_Middleware_Without_DefaultPipeline_No_Other_Middleware_Registered()
+    {
+        // arrange
+        using var demoProject = await DemoProject.CreateAsync();
+
+        var fusionGraph =
+            await new FusionGraphComposer(logFactory: _logFactory)
+                .ComposeAsync(new[] { demoProject.Accounts.ToConfiguration() });
+
+        var config = new DemoIntegrationTests.HotReloadConfiguration(
+            new GatewayConfiguration(
+                SchemaFormatter.FormatAsDocument(fusionGraph)));
+
+        var executor = await new ServiceCollection()
+            .AddSingleton(demoProject.HttpClientFactory)
+            .AddFusionGatewayServer()
+            .RegisterGatewayConfiguration(_ => config)
+            .UseRequest<TestMiddleware>()
+            .BuildRequestExecutorAsync();
+
+        // act
+        var result = await executor.ExecuteAsync("{ __typename }");
+
+        // assert
+        result.MatchInlineSnapshot("""
+                                   {
+                                     "data": {
+                                       "result": true
+                                     },
+                                     "extensions": {
+                                       "state": "default pipeline didn't run"
+                                     }
+                                   }
+                                   """);
+    }
+
+    private class TestMiddleware(RequestDelegate next)
+    {
+        public async ValueTask InvokeAsync(
+            IRequestContext context,
+            IBatchDispatcher batchDispatcher)
+        {
+            if (context.ContextData.ContainsKey("short-circuit"))
+            {
+                context.Result = OperationResultBuilder.New()
+                    .SetData(new Dictionary<string, object?> { ["result"] = true })
+                    .AddExtension("state", "custom middleware short-circuited")
+                    .Build();
+                return;
+            }
+
+            await next(context);
+
+            if (context.Result is not IOperationResult)
+            {
+                context.Result = OperationResultBuilder.New()
+                    .SetData(new Dictionary<string, object?> { ["result"] = true })
+                    .AddExtension("state", "default pipeline didn't run")
+                    .Build();
+            }
+        }
+    }
+}