Include known providers in error message when provider is not found

src/Orleans.Core/Core/DefaultClientServices.cs

@@ -1,31 +1,32 @@
 #nullable enable
-using Orleans.Configuration;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
 using Microsoft.AspNetCore.Connections;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Options;
+using Orleans.Configuration;
 using Orleans.Configuration.Internal;
 using Orleans.Configuration.Validators;
 using Orleans.GrainReferences;
+using Orleans.Hosting;
 using Orleans.Messaging;
 using Orleans.Metadata;
 using Orleans.Networking.Shared;
+using Orleans.Placement.Repartitioning;
 using Orleans.Providers;
 using Orleans.Runtime;
 using Orleans.Runtime.Messaging;
 using Orleans.Runtime.Versions;
 using Orleans.Serialization;
-using Orleans.Statistics;
-using Orleans.Serialization.Serializers;
 using Orleans.Serialization.Cloning;
-using Microsoft.Extensions.Hosting;
-using System.Collections.Generic;
 using Orleans.Serialization.Internal;
-using System;
-using Orleans.Hosting;
-using System.Reflection;
-using Microsoft.Extensions.Configuration;
-using Orleans.Placement.Repartitioning;
+using Orleans.Serialization.Serializers;
+using Orleans.Statistics;
 
 namespace Orleans
 {
@@ -210,7 +211,17 @@ static IProviderBuilder<IClientBuilder> GetRequiredProvider(Dictionary<(string K
                         ?? throw new InvalidOperationException($"{kind} provider, '{name}', of type {type}, does not implement {typeof(IProviderBuilder<IClientBuilder>)}.");
                 }
 
-                throw new InvalidOperationException($"Could not find {kind} provider named '{name}'. This can indicate that either the 'Microsoft.Orleans.Sdk' package the provider's package are not referenced by your application.");
+                var knownProvidersOfKind = knownProviderTypes
+                    .Where(kvp => string.Equals(kvp.Key.Kind, kind, StringComparison.OrdinalIgnoreCase))
+                    .Select(kvp => kvp.Key.Name)
+                    .OrderBy(n => n)
+                    .ToList();
+
+                var knownProvidersMessage = knownProvidersOfKind.Count > 0
+                    ? $" Known {kind} providers: {string.Join(", ", knownProvidersOfKind)}."
+                    : string.Empty;
+
+                throw new InvalidOperationException($"Could not find {kind} provider named '{name}'. This can indicate that either the 'Microsoft.Orleans.Sdk' or the provider's package are not referenced by your application.{knownProvidersMessage}");
             }
 
             static Dictionary<(string Kind, string Name), Type> GetRegisteredProviders()

src/Orleans.Runtime/Hosting/DefaultSiloServices.cs

@@ -475,7 +475,17 @@ static IProviderBuilder<ISiloBuilder> GetRequiredProvider(Dictionary<(string Kin
                         ?? throw new InvalidOperationException($"{kind} provider, '{name}', of type {type}, does not implement {typeof(IProviderBuilder<ISiloBuilder>)}.");
                 }
 
-                throw new InvalidOperationException($"Could not find {kind} provider named '{name}'. This can indicate that either the 'Microsoft.Orleans.Sdk' or the provider's package are not referenced by your application.");
+                var knownProvidersOfKind = knownProviderTypes
+                    .Where(kvp => string.Equals(kvp.Key.Kind, kind, StringComparison.OrdinalIgnoreCase))
+                    .Select(kvp => kvp.Key.Name)
+                    .OrderBy(n => n)
+                    .ToList();
+
+                var knownProvidersMessage = knownProvidersOfKind.Count > 0
+                    ? $" Known {kind} providers: {string.Join(", ", knownProvidersOfKind)}."
+                    : string.Empty;
+
+                throw new InvalidOperationException($"Could not find {kind} provider named '{name}'. This can indicate that either the 'Microsoft.Orleans.Sdk' or the provider's package are not referenced by your application.{knownProvidersMessage}");
             }
 
             static Dictionary<(string Kind, string Name), Type> GetRegisteredProviders()

test/NonSilo.Tests/ProviderErrorMessageTests.cs

@@ -0,0 +1,122 @@
+#nullable enable
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Hosting;
+using Orleans.Hosting;
+using Xunit;
+
+namespace NonSilo.Tests
+{
+    /// <summary>
+    /// Tests for provider error messages to ensure they include helpful information about known/registered providers.
+    /// These tests verify that when a provider is not found, the error message includes a list of available providers
+    /// for the specified kind (e.g., Clustering, GrainStorage, etc.) to help users diagnose configuration issues.
+    /// </summary>
+    [TestCategory("BVT")]
+    [TestCategory("Providers")]
+    public class ProviderErrorMessageTests
+    {
+        /// <summary>
+        /// Tests that client builder includes known providers in error message when a provider is not found.
+        /// Verifies that the error message contains both the standard message and a list of known providers
+        /// for the specified kind when an invalid provider type is requested.
+        /// </summary>
+        [Fact]
+        public void ClientBuilder_IncludesKnownProvidersInErrorMessage()
+        {
+            var configDict = new Dictionary<string, string?>
+            {
+                { "Orleans:ClusterId", "test-cluster" },
+                { "Orleans:ServiceId", "test-service" },
+                { "Orleans:Clustering:ProviderType", "NonExistentProvider" }
+            };
+
+            var exception = Assert.Throws<InvalidOperationException>(() =>
+            {
+                _ = new HostBuilder()
+                    .ConfigureAppConfiguration(configBuilder =>
+                    {
+                        configBuilder.AddInMemoryCollection(configDict);
+                    })
+                    .UseOrleansClient(_ => { })
+                    .Build();
+            });
+
+            // Verify the error message contains the provider name that was not found
+            Assert.Contains("Could not find Clustering provider named 'NonExistentProvider'", exception.Message);
+
+            // Verify the error message includes information about known providers
+            // The exact list will depend on what providers are registered, but the message should contain "Known Clustering providers:"
+            // if there are any registered Clustering providers
+            Assert.Contains("This can indicate that either the 'Microsoft.Orleans.Sdk' or the provider's package are not referenced", exception.Message);
+        }
+
+        /// <summary>
+        /// Tests that silo builder includes known providers in error message when a provider is not found.
+        /// Verifies that the error message contains both the standard message and a list of known providers
+        /// for the specified kind when an invalid provider type is requested.
+        /// </summary>
+        [Fact]
+        public void SiloBuilder_IncludesKnownProvidersInErrorMessage()
+        {
+            var configDict = new Dictionary<string, string?>
+            {
+                { "Orleans:ClusterId", "test-cluster" },
+                { "Orleans:ServiceId", "test-service" },
+                { "Orleans:Clustering:ProviderType", "NonExistentProvider" }
+            };
+
+            var exception = Assert.Throws<InvalidOperationException>(() =>
+            {
+                _ = new HostBuilder()
+                    .ConfigureAppConfiguration(configBuilder =>
+                    {
+                        configBuilder.AddInMemoryCollection(configDict);
+                    })
+                    .UseOrleans(_ => { })
+                    .Build();
+            });
+
+            // Verify the error message contains the provider name that was not found
+            Assert.Contains("Could not find Clustering provider named 'NonExistentProvider'", exception.Message);
+
+            // Verify the error message includes information about known providers
+            Assert.Contains("This can indicate that either the 'Microsoft.Orleans.Sdk' or the provider's package are not referenced", exception.Message);
+        }
+
+        /// <summary>
+        /// Tests that error message for GrainStorage provider includes known providers.
+        /// Verifies that when an invalid GrainStorage provider is specified, the error message
+        /// includes helpful information about available GrainStorage providers.
+        /// </summary>
+        [Fact]
+        public void SiloBuilder_IncludesKnownGrainStorageProvidersInErrorMessage()
+        {
+            var configDict = new Dictionary<string, string?>
+            {
+                { "Orleans:ClusterId", "test-cluster" },
+                { "Orleans:ServiceId", "test-service" },
+                { "Orleans:GrainStorage:MyStorage:ProviderType", "InvalidStorageProvider" }
+            };
+
+            var exception = Assert.Throws<InvalidOperationException>(() =>
+            {
+                _ = new HostBuilder()
+                    .ConfigureAppConfiguration(configBuilder =>
+                    {
+                        configBuilder.AddInMemoryCollection(configDict);
+                    })
+                    .UseOrleans(siloBuilder =>
+                    {
+                        siloBuilder.UseLocalhostClustering();
+                    })
+                    .Build();
+            });
+
+            // Verify the error message contains the provider name that was not found
+            Assert.Contains("Could not find GrainStorage provider named 'InvalidStorageProvider'", exception.Message);
+
+            // Verify the error message includes information about known providers
+            Assert.Contains("This can indicate that either the 'Microsoft.Orleans.Sdk' or the provider's package are not referenced", exception.Message);
+        }
+    }
+}