Simplify validation and make it possible to opt-out from it

Author: danielmarbach

src/Tests/ApprovalFiles/APIApprovals.Approve.approved.txt

@@ -100,10 +100,11 @@ namespace NServiceBus
     }
     public abstract class TopicTopology
     {
-        protected TopicTopology(NServiceBus.Transport.AzureServiceBus.TopologyOptions options) { }
+        protected TopicTopology(NServiceBus.Transport.AzureServiceBus.TopologyOptions options, Microsoft.Extensions.Options.IValidateOptions<NServiceBus.Transport.AzureServiceBus.TopologyOptions> optionsValidator) { }
         [System.Obsolete("Use `MigrationTopology.IsHierarchy` instead. The member currently throws a NotImp" +
             "lementedException. Will be removed in version 6.0.0.", true)]
         public bool IsHierarchy { get; }
+        public Microsoft.Extensions.Options.IValidateOptions<NServiceBus.Transport.AzureServiceBus.TopologyOptions> OptionsValidator { get; set; }
         [System.Obsolete("Use `MigrationTopology.TopicToPublishTo` instead. The member currently throws a N" +
             "otImplementedException. Will be removed in version 6.0.0.", true)]
         public string TopicToPublishTo { get; }
@@ -255,6 +256,11 @@ namespace NServiceBus.Transport.AzureServiceBus
         [System.Text.Json.Serialization.JsonInclude]
         public System.Collections.Generic.Dictionary<string, System.Collections.Generic.HashSet<string>> SubscribedEventToTopicsMap { get; init; }
     }
+    public sealed class TopologyOptionsDisableValidationValidator : Microsoft.Extensions.Options.IValidateOptions<NServiceBus.Transport.AzureServiceBus.TopologyOptions>
+    {
+        public TopologyOptionsDisableValidationValidator() { }
+        public Microsoft.Extensions.Options.ValidateOptionsResult Validate(string name, NServiceBus.Transport.AzureServiceBus.TopologyOptions options) { }
+    }
     [System.Text.Json.Serialization.JsonSerializable(typeof(NServiceBus.Transport.AzureServiceBus.MigrationTopologyOptions))]
     [System.Text.Json.Serialization.JsonSerializable(typeof(NServiceBus.Transport.AzureServiceBus.TopologyOptions))]
     [System.Text.Json.Serialization.JsonSourceGenerationOptions(WriteIndented=true)]

src/Tests/EventRouting/MigrationTopologyTests.cs

@@ -57,6 +57,22 @@ public void Should_self_validate_consistency()
         Approver.Verify(validationException.Message);
     }
 
+    // With the generic host validation can already be done at startup and this allows disabling further validation
+    // for advanced scenarios to save startup time.
+    [Test]
+    public void Should_allow_disabling_validation()
+    {
+        var topologyOptions = new MigrationTopologyOptions
+        {
+            TopicToPublishTo = new string('a', 261), TopicToSubscribeOn = new string('a', 261)
+        };
+
+        var topology = TopicTopology.FromOptions(topologyOptions);
+        topology.OptionsValidator = new TopologyOptionsDisableValidationValidator();
+
+        Assert.DoesNotThrow(() => topology.Validate());
+    }
+
     class MyEvent;
     class MyEventMappedTwice;
 }

src/Tests/EventRouting/TopicPerEventTopologyTests.cs

@@ -42,5 +42,21 @@ public void Should_self_validate()
         Approver.Verify(validationException.Message);
     }
 
+    // With the generic host validation can already be done at startup and this allows disabling further validation
+    // for advanced scenarios to save startup time.
+    [Test]
+    public void Should_allow_disabling_validation()
+    {
+        var topologyOptions = new TopologyOptions
+        {
+            PublishedEventToTopicsMap = { { typeof(MyEvent).FullName, new string('c', 261) } }
+        };
+
+        var topology = TopicTopology.FromOptions(topologyOptions);
+        topology.OptionsValidator = new TopologyOptionsDisableValidationValidator();
+
+        Assert.DoesNotThrow(() => topology.Validate());
+    }
+
     class MyEvent;
 }

src/Transport/EventRouting/MigrationTopology.cs

@@ -1,13 +1,16 @@
 namespace NServiceBus.Transport.AzureServiceBus;
 
 using System;
+using Microsoft.Extensions.Options;
 
 /// <summary>
 /// Topology that allows mixing of single-topic and topic-per-event approaches in order to allow gradual migration to the topic-per-event topology.
 /// </summary>
 public sealed class MigrationTopology : TopicTopology
 {
-    internal MigrationTopology(MigrationTopologyOptions options) : base(options) => Options = options;
+    internal MigrationTopology(MigrationTopologyOptions options) : base(options,
+        new OptionsValidatorDecorator(new MigrationTopologyOptionsValidator())) =>
+        Options = options;
 
     /// <summary>
     /// Gets the topic name of the topic where all single-topic events are published to.
@@ -182,4 +185,13 @@ protected override string GetPublishDestinationCore(string eventTypeFullName)
     }
 
     internal override SubscriptionManager CreateSubscriptionManager(SubscriptionManagerCreationOptions creationOptions) => new MigrationTopologySubscriptionManager(creationOptions, Options);
+
+    sealed class OptionsValidatorDecorator(IValidateOptions<MigrationTopologyOptions> decorated)
+        : IValidateOptions<TopologyOptions>
+    {
+        public ValidateOptionsResult Validate(string? name, TopologyOptions options) =>
+            decorated.Validate(name,
+                options as MigrationTopologyOptions ??
+                throw new Exception("The options to be validated must be of type MigrationTopologyOptions."));
+    }
 }

src/Transport/EventRouting/TopicPerEventTopology.cs

@@ -8,7 +8,7 @@ namespace NServiceBus.Transport.AzureServiceBus;
 /// </summary>
 public sealed class TopicPerEventTopology : TopicTopology
 {
-    internal TopicPerEventTopology(TopologyOptions options) : base(options)
+    internal TopicPerEventTopology(TopologyOptions options) : base(options, new TopologyOptionsValidator())
     {
     }
 

src/Transport/EventRouting/TopicTopology.cs

@@ -14,7 +14,16 @@ public abstract partial class TopicTopology
         /// <summary>
         /// Allows creating topology instances based on serializable state
         /// </summary>
-        protected TopicTopology(TopologyOptions options) => Options = options;
+        protected TopicTopology(TopologyOptions options, IValidateOptions<TopologyOptions> optionsValidator)
+        {
+            Options = options;
+            OptionsValidator = optionsValidator;
+        }
+
+        /// <summary>
+        /// Gets or sets the options validator used to validate the consistency of the provided options.
+        /// </summary>
+        public IValidateOptions<TopologyOptions> OptionsValidator { get; set; }
 
         internal TopologyOptions Options { get; }
 
@@ -77,18 +86,7 @@ public static MigrationTopology MigrateFromTopicHierarchy(string topicToPublishT
         /// </summary>
         public void Validate()
         {
-            ValidateOptionsResult validationResult;
-
-            if (Options is MigrationTopologyOptions migrationOptions)
-            {
-                var migrationOptionsValidator = new MigrationTopologyOptionsValidator();
-                validationResult = migrationOptionsValidator.Validate(null, migrationOptions);
-            }
-            else
-            {
-                var validator = new TopologyOptionsValidator();
-                validationResult = validator.Validate(null, Options);
-            }
+            ValidateOptionsResult validationResult = OptionsValidator.Validate(null, Options);
 
             if (validationResult.Succeeded)
             {

src/Transport/EventRouting/TopologyOptionsDisableValidationValidator.cs

@@ -0,0 +1,12 @@
+namespace NServiceBus.Transport.AzureServiceBus;
+
+using Microsoft.Extensions.Options;
+
+/// <summary>
+/// Does not validate the provided <see cref="TopologyOptions"/>.
+/// </summary>
+public sealed class TopologyOptionsDisableValidationValidator : IValidateOptions<TopologyOptions>
+{
+    /// <inheritdoc />
+    public ValidateOptionsResult Validate(string name, TopologyOptions options) => ValidateOptionsResult.Success;
+}