Add OpenAPI test project

Author: commonsensesoftware

asp.slnx

@@ -124,6 +124,7 @@
     <Project Path="src/AspNetCore/WebApi/test/Asp.Versioning.Http.Tests/Asp.Versioning.Http.Tests.csproj" />
     <Project Path="src/AspNetCore/WebApi/test/Asp.Versioning.Mvc.ApiExplorer.Tests/Asp.Versioning.Mvc.ApiExplorer.Tests.csproj" />
     <Project Path="src/AspNetCore/WebApi/test/Asp.Versioning.Mvc.Tests/Asp.Versioning.Mvc.Tests.csproj" />
+    <Project Path="src/AspNetCore/WebApi/test/Asp.Versioning.OpenApi.Tests/Asp.Versioning.OpenApi.Tests.csproj" />
   </Folder>
   <Folder Name="/src/Client/" />
   <Folder Name="/src/Client/src/">

src/AspNetCore/WebApi/test/Asp.Versioning.OpenApi.Tests/Asp.Versioning.OpenApi.Tests.csproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+ <PropertyGroup>
+  <TargetFramework>$(DefaultTargetFramework)</TargetFramework>
+  <RootNamespace>Asp.Versioning.OpenApi</RootNamespace>
+ </PropertyGroup>
+
+ <ItemGroup>
+   <ProjectReference Include="..\..\src\Asp.Versioning.OpenApi\Asp.Versioning.OpenApi.csproj" />
+ </ItemGroup>
+
+</Project>

src/AspNetCore/WebApi/test/Asp.Versioning.OpenApi.Tests/OpenApiDocumentDescriptionOptionsTest.cs

@@ -0,0 +1,37 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+
+
+namespace Asp.Versioning.OpenApi;
+
+public class OpenApiDocumentDescriptionOptionsTest
+{
+    [Fact]
+    public void sunset_notice_should_be_null_without_a_date()
+    {
+        // arrange
+        var options = new OpenApiDocumentDescriptionOptions();
+        var policy = new SunsetPolicy();
+
+        // act
+        var actual = options.SunsetNotice( policy );
+
+        // assert
+        actual.Should().BeNull();
+    }
+
+    [Fact]
+    public void sunset_notice_should_return_expected_message()
+    {
+        // arrange
+        var expected = "The API will be sunset on 2/8/2026.";
+        var options = new OpenApiDocumentDescriptionOptions();
+        var date = new DateTimeOffset( new DateTime( 2026, 2, 8 ) );
+        var policy = new SunsetPolicy( date );
+
+        // act
+        var actual = options.SunsetNotice( policy );
+
+        // assert
+        actual.Should().Be( expected );
+    }
+}