✨ Add and verify .NET 10 minimal API validation support with DataAnnotations

src/OptionalValues/OptionalValue.cs

@@ -75,6 +75,7 @@ public OptionalValue(T value)
         "Design",
         "CA1000:Do not declare static members on generic types",
         Justification = "Having a static class for Unspecified is not adding value at the moment")]
+    [JsonIgnore]
     public static OptionalValue<T> Unspecified => new();
 
     /// <summary>

test/OptionalValues.DataAnnotations.Tests/MinimalApiValidationTest.cs

@@ -0,0 +1,133 @@
+using System.ComponentModel.DataAnnotations;
+using System.Net;
+using System.Net.Http.Json;
+
+using Shouldly;
+
+#if NET10_0_OR_GREATER
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+#endif
+
+namespace OptionalValues.DataAnnotations.Tests;
+
+/// <summary>
+/// Tests that verify OptionalValues DataAnnotations work with .NET 10's minimal API validation support.
+/// In .NET 10, minimal APIs automatically validate models when AddValidation() is called.
+/// See: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis?view=aspnetcore-10.0#validation-support-in-minimal-apis
+/// 
+/// These tests create an actual minimal API with host builder and use AddValidation() to verify
+/// that OptionalValues DataAnnotations work correctly with automatic validation.
+/// </summary>
+#if NET10_0_OR_GREATER
+public class MinimalApiValidationTest : IAsyncLifetime
+{
+    private WebApplication? _app;
+    private HttpClient? _client;
+
+    public class TestModel
+    {
+        [RequiredValue]
+        public OptionalValue<string> RequiredName { get; init; }
+
+        [OptionalRange(1, 100)]
+        public OptionalValue<int> RangeValue { get; init; }
+
+        [Specified]
+        public OptionalValue<string?> SpecifiedField { get; init; }
+    }
+
+    public async Task InitializeAsync()
+    {
+        // Create a minimal API host with AddValidation()
+        var builder = WebApplication.CreateBuilder();
+
+        // Configure JSON options for OptionalValue support
+        builder.Services.ConfigureHttpJsonOptions(options =>
+        {
+            options.SerializerOptions.AddOptionalValueSupport();
+        });
+
+        // Add validation support for minimal APIs in .NET 10
+        builder.Services.AddValidation();
+
+        // Use test server
+        builder.WebHost.UseTestServer();
+
+        _app = builder.Build();
+
+        // Create minimal API endpoint with automatic validation
+        _app.MapPost("/test", (TestModel model) => Results.Ok(model))
+            .WithName("TestEndpoint");
+
+        await _app.StartAsync();
+        _client = _app.GetTestClient();
+    }
+
+    public async Task DisposeAsync()
+    {
+        if (_app != null)
+        {
+            await _app.DisposeAsync();
+        }
+        _client?.Dispose();
+    }
+
+    [Fact]
+    public async Task ValidModel_ShouldPass_MinimalApiValidation()
+    {
+        // Arrange - Send valid JSON
+        var json = """{"RequiredName":"TestName","RangeValue":50,"SpecifiedField":"value"}""";
+        var content = new StringContent(json, System.Text.Encoding.UTF8, "application/json");
+
+        // Act - Post to minimal API which uses AddValidation()
+        var response = await _client!.PostAsync("/test", content);
+
+        // Assert
+        response.StatusCode.ShouldBe(HttpStatusCode.OK);
+    }
+
+    [Fact]
+    public async Task InvalidModel_ShouldFail_MinimalApiValidation()
+    {
+        // Arrange - Send invalid JSON (out of range value)
+        var json = """{"RequiredName":"Test","RangeValue":150,"SpecifiedField":"value"}""";
+        var content = new StringContent(json, System.Text.Encoding.UTF8, "application/json");
+
+        // Act - Post to minimal API which uses AddValidation()
+        var response = await _client!.PostAsync("/test", content);
+
+        // Assert - Minimal API validation should return BadRequest
+        response.StatusCode.ShouldBe(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task UnspecifiedOptionalFields_ShouldBeValid_MinimalApiValidation()
+    {
+        // Arrange - Don't send unspecified fields in JSON
+        var json = """{"RequiredName":"Test","SpecifiedField":null}""";
+        var content = new StringContent(json, System.Text.Encoding.UTF8, "application/json");
+
+        // Act - Post to minimal API which uses AddValidation()
+        var response = await _client!.PostAsync("/test", content);
+
+        // Assert
+        response.StatusCode.ShouldBe(HttpStatusCode.OK);
+    }
+}
+#else
+public class MinimalApiValidationTest
+{
+    [Fact]
+    public void MinimalApiValidation_OnlyAvailableInNet10()
+    {
+        // Minimal API validation with AddValidation() is only available in .NET 10+
+        true.ShouldBeTrue();
+    }
+}
+#endif
+

test/OptionalValues.DataAnnotations.Tests/OptionalValues.DataAnnotations.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
@@ -20,6 +20,11 @@
     </PackageReference>
   </ItemGroup>
 
+  <!-- Only include Microsoft.AspNetCore.Mvc.Testing for net10.0 where minimal API validation is available -->
+  <ItemGroup Condition="'$(TargetFramework)' == 'net10.0'">
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" />
+  </ItemGroup>
+
   <ItemGroup>
     <Using Include="Xunit" />
   </ItemGroup>

version.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://raw.githubusercontent.com/dotnet/Nerdbank.GitVersioning/main/src/NerdBank.GitVersioning/version.schema.json",
-  "version": "0.8",
+  "version": "0.9",
   "publicReleaseRefSpec": [
     "^refs/heads/main$",
     "^refs/heads/v\\d+(?:\\.\\d+)?$",