Add describe-routing sub-command to wolverine-diagnostics (#2468)

docs/guide/command-line.md

@@ -154,7 +154,12 @@ builder.Services.DisableAllWolverineMessagePersistence();
 ## Wolverine Diagnostics Commands <Badge type="tip" text="5.14" />
 
 The `wolverine-diagnostics` command is an extensible parent command for deeper Wolverine-specific
-inspection tools. Currently it exposes one sub-command: **`codegen-preview`**.
+inspection tools.
+
+::: tip
+Both `codegen-preview` and `describe-routing` work without database or message-broker connectivity.
+Wolverine automatically detects CLI codegen mode and stubs out persistence and transports.
+:::
 
 ### codegen-preview
 
@@ -187,11 +192,44 @@ middleware calls in order, dependency resolution from the IoC container, and any
 transaction-wrapping frames. This is identical to what `codegen preview` outputs, but scoped to
 exactly one handler so the signal-to-noise ratio is much higher.
 
-::: tip
-`wolverine-diagnostics` works without database or message-broker connectivity for the same reason
-as `codegen preview`: Wolverine automatically detects CLI codegen mode and stubs out persistence
-and transports.
-:::
+### describe-routing <Badge type="tip" text="5.15" />
+
+Inspect the message routing configuration for a specific message type or show a complete view of
+all message routing in your application.
+
+**Inspect routing for a single message type** (accepts full name, short name, or fuzzy match):
+
+```bash
+# Short class name
+dotnet run -- wolverine-diagnostics describe-routing CreateOrder
+
+# Fully-qualified name
+dotnet run -- wolverine-diagnostics describe-routing MyApp.Orders.CreateOrder
+```
+
+The output for a single message type includes:
+
+- **Local handler** — the handler class and method, if any
+- **Routes table** — each destination with its type (local vs. external), endpoint mode
+  (Buffered/Durable/Inline), outbox enrollment, serialization format, and how the route was
+  resolved (local handler convention, explicit publish rule, transport routing convention, or
+  `[LocalQueue]` attribute)
+- **Message-level attributes** — any `ModifyEnvelopeAttribute`-derived attributes (e.g.,
+  `[DeliverWithin]`) applied to the message class
+
+**Show the complete routing topology** (all message types):
+
+```bash
+dotnet run -- wolverine-diagnostics describe-routing --all
+```
+
+The `--all` output includes:
+
+- **Routing Conventions** — transport-level conventions registered via `RouteWith()`
+- **Message Routing** table — every known message type with its destinations, mode, outbox status,
+  and serializer; unrouted types are flagged in yellow
+- **Listeners** — all configured listening endpoints with name, mode, and parallelism
+- **Senders** — all configured sending endpoints with name, mode, and subscription count
 
 ## Other Highlights
 

src/Testing/CoreTests/Diagnostics/WolverineDiagnosticsCommandTests.cs

@@ -4,6 +4,7 @@
 using Microsoft.Extensions.Hosting;
 using Shouldly;
 using Wolverine.Diagnostics;
+using Wolverine.Runtime;
 using Wolverine.Runtime.Handlers;
 using Xunit;
 
@@ -141,12 +142,146 @@ public async Task codegen_preview_generates_code_for_handler()
             DynamicCodeBuilder.WithinCodegenCommand = false;
         }
     }
+
+    // ── FindMessageType ─────────────────────────────────────────────────────────
+
+    [Fact]
+    public async Task find_message_type_by_exact_full_name()
+    {
+        var (messageTypes, graph) = await BuildMessageTypesAsync();
+        var found = WolverineDiagnosticsCommand.FindMessageType(
+            "CoreTests.Diagnostics.DiagnosticsTestMessage", messageTypes, graph);
+        found.ShouldBe(typeof(DiagnosticsTestMessage));
+    }
+
+    [Fact]
+    public async Task find_message_type_by_short_name()
+    {
+        var (messageTypes, graph) = await BuildMessageTypesAsync();
+        var found = WolverineDiagnosticsCommand.FindMessageType(
+            "DiagnosticsTestMessage", messageTypes, graph);
+        found.ShouldBe(typeof(DiagnosticsTestMessage));
+    }
+
+    [Fact]
+    public async Task find_message_type_fuzzy_contains()
+    {
+        var (messageTypes, graph) = await BuildMessageTypesAsync();
+        var found = WolverineDiagnosticsCommand.FindMessageType(
+            "TestMessage", messageTypes, graph);
+        found.ShouldBe(typeof(DiagnosticsTestMessage));
+    }
+
+    [Fact]
+    public async Task find_message_type_returns_null_for_unknown()
+    {
+        var (messageTypes, graph) = await BuildMessageTypesAsync();
+        var found = WolverineDiagnosticsCommand.FindMessageType(
+            "NonExistentXyzMessage", messageTypes, graph);
+        found.ShouldBeNull();
+    }
+
+    // ── describe-routing smoke tests ─────────────────────────────────────────
+
+    [Fact]
+    public async Task describe_routing_handled_message_is_known_to_handler_graph()
+    {
+        // Note: in MediatorOnly (lightweight) mode, local routing assignments are not populated,
+        // so runtime.RoutingFor() returns no routes. We verify discovery and CanHandle instead.
+        DynamicCodeBuilder.WithinCodegenCommand = true;
+        try
+        {
+            using var host = await Host.CreateDefaultBuilder()
+                .UseWolverine(opts =>
+                {
+                    opts.Discovery
+                        .DisableConventionalDiscovery()
+                        .IncludeType(typeof(DiagnosticsTestHandler));
+                })
+                .StartAsync();
+
+            var runtime = host.Services.GetRequiredService<IWolverineRuntime>();
+            var options = runtime.Options;
+            var messageTypes = options.Discovery.FindAllMessages(options.HandlerGraph).ToList();
+
+            var match = WolverineDiagnosticsCommand.FindMessageType(
+                "DiagnosticsTestMessage", messageTypes, options.HandlerGraph);
+
+            match.ShouldNotBeNull();
+            match.ShouldBe(typeof(DiagnosticsTestMessage));
+            options.HandlerGraph.CanHandle(typeof(DiagnosticsTestMessage))
+                .ShouldBeTrue("handler graph should know about the handled message type");
+        }
+        finally
+        {
+            DynamicCodeBuilder.WithinCodegenCommand = false;
+        }
+    }
+
+    [Fact]
+    public async Task describe_routing_for_unhandled_message_returns_no_routes()
+    {
+        DynamicCodeBuilder.WithinCodegenCommand = true;
+        try
+        {
+            using var host = await Host.CreateDefaultBuilder()
+                .UseWolverine(opts =>
+                {
+                    opts.Discovery.DisableConventionalDiscovery();
+                })
+                .StartAsync();
+
+            var runtime = host.Services.GetRequiredService<IWolverineRuntime>();
+            WolverineSystemPart.WithinDescription = true;
+            try
+            {
+                var routes = runtime.RoutingFor(typeof(DiagnosticsUnhandledMessage)).Routes;
+                routes.ShouldBeEmpty();
+            }
+            finally
+            {
+                WolverineSystemPart.WithinDescription = false;
+            }
+        }
+        finally
+        {
+            DynamicCodeBuilder.WithinCodegenCommand = false;
+        }
+    }
+
+    private static async Task<(IReadOnlyList<Type> messageTypes, HandlerGraph graph)> BuildMessageTypesAsync()
+    {
+        DynamicCodeBuilder.WithinCodegenCommand = true;
+        try
+        {
+            using var host = await Host.CreateDefaultBuilder()
+                .UseWolverine(opts =>
+                {
+                    opts.Discovery
+                        .DisableConventionalDiscovery()
+                        .IncludeType(typeof(DiagnosticsTestHandler));
+                })
+                .StartAsync();
+
+            var graph = host.Services.GetRequiredService<HandlerGraph>();
+            var options = host.Services.GetRequiredService<IWolverineRuntime>().Options;
+            var messageTypes = options.Discovery.FindAllMessages(graph);
+            return (messageTypes, graph);
+        }
+        finally
+        {
+            DynamicCodeBuilder.WithinCodegenCommand = false;
+        }
+    }
 }
 
 // ── Test fixtures ────────────────────────────────────────────────────────────
 
 public record DiagnosticsTestMessage(string Text);
 
+// Unhandled message — no handler registered
+public record DiagnosticsUnhandledMessage(string Text);
+
 public static class DiagnosticsTestHandler
 {
     public static void Handle(DiagnosticsTestMessage message)