Do not consider abstract classes in configuration options (#362)

Author: gsteenpa

src/Microsoft.Azure.WebJobs.Extensions.OpenApi.Core/Resolvers/OpenApiConfigurationResolver.cs

@@ -23,6 +23,7 @@ public static IOpenApiConfigurationOptions Resolve(Assembly assembly)
         {
             var type = assembly.GetLoadableTypes()
                                .SingleOrDefault(p => p.GetInterface("IOpenApiConfigurationOptions", ignoreCase: true).IsNullOrDefault() == false
+                                                  && p.IsAbstract == false
                                                   && p.GetCustomAttribute<ObsoleteAttribute>(inherit: false).IsNullOrDefault() == true);
             if (type.IsNullOrDefault())
             {

test/Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Tests.Fakes/FakeOpenApiConfigurationOptions.cs

@@ -0,0 +1,6 @@
+namespace Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Tests.Fakes
+{
+    public class FakeOpenApiConfigurationOptions : FakeOpenApiConfigurationOptionsBase
+    {
+    }
+}

test/Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Tests.Fakes/FakeOpenApiConfigurationOptionsBase.cs

@@ -0,0 +1,8 @@
+using Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Configurations;
+
+namespace Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Tests.Fakes
+{
+    public abstract class FakeOpenApiConfigurationOptionsBase : DefaultOpenApiConfigurationOptions
+    {
+    }
+}

test/Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Tests/Resolvers/OpenApiConfigurationResolverTests.cs

@@ -5,6 +5,7 @@
 using Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Abstractions;
 using Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Configurations;
 using Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Resolvers;
+using Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Tests.Fakes;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
 namespace Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Tests.Resolvers
@@ -39,5 +40,16 @@ public void Given_Assembly_When_Resolve_Invoked_Then_It_Should_Return_Result()
 
             result.Should().BeOfType<DefaultOpenApiConfigurationOptions>();
         }
+
+        [TestMethod]
+        public void Given_An_Assembly_With_An_Abstract_Base_Configuration_Then_It_Should_Return_Result()
+        {
+            var assembly = Assembly.GetAssembly(typeof(FakeOpenApiConfigurationOptions));
+
+            var result = OpenApiConfigurationResolver.Resolve(assembly);
+
+            result.Should().BeOfType<FakeOpenApiConfigurationOptions>();
+            result.GetType().BaseType.Should().Be(typeof(FakeOpenApiConfigurationOptionsBase)); // This verifies the abstract type was considered in the resolution
+        }
     }
 }