Correct regression from custom group names. Fixes #923

Author: commonsensesoftware

src/AspNetCore/WebApi/src/Asp.Versioning.Mvc.ApiExplorer/VersionedApiDescriptionProvider.cs

@@ -156,11 +156,11 @@ public virtual void OnProvidersExecuted( ApiDescriptionProviderContext context )
                 var groupResult = result.Clone();
                 var metadata = action.GetApiVersionMetadata();
 
-                if ( string.IsNullOrEmpty( groupResult.GroupName ) || formatGroupName is null )
+                if ( string.IsNullOrEmpty( groupResult.GroupName ) )
                 {
                     groupResult.GroupName = formattedVersion;
                 }
-                else
+                else if ( formatGroupName is not null )
                 {
                     groupResult.GroupName = formatGroupName( groupResult.GroupName, formattedVersion );
                 }

src/AspNetCore/WebApi/test/Asp.Versioning.Mvc.ApiExplorer.Tests/TestActionDescriptorCollectionProvider.cs

@@ -9,6 +9,26 @@ internal sealed class TestActionDescriptorCollectionProvider : IActionDescriptor
 {
     private readonly Lazy<ActionDescriptorCollection> collection = new( CreateActionDescriptors );
 
+    public TestActionDescriptorCollectionProvider() { }
+
+    public TestActionDescriptorCollectionProvider( ActionDescriptor action, params ActionDescriptor[] otherActions )
+    {
+        ActionDescriptor[] actions;
+
+        if ( otherActions.Length == 0 )
+        {
+            actions = new ActionDescriptor[] { action };
+        }
+        else
+        {
+            actions = new ActionDescriptor[otherActions.Length];
+            actions[0] = action;
+            Array.Copy( otherActions, 0, actions, 1, otherActions.Length );
+        }
+
+        collection = new( () => new( actions, 0 ) );
+    }
+
     public ActionDescriptorCollection ActionDescriptors => collection.Value;
 
     private static ActionDescriptorCollection CreateActionDescriptors()

src/AspNetCore/WebApi/test/Asp.Versioning.Mvc.ApiExplorer.Tests/VersionedApiDescriptionProviderTest.cs

@@ -2,6 +2,7 @@
 
 namespace Asp.Versioning.ApiExplorer;
 
+using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Metadata;
@@ -92,6 +93,62 @@ public void versioned_api_explorer_should_apply_sunset_policy()
                .BeTrue();
     }
 
+    [Fact]
+    public void versioned_api_explorer_should_preserve_group_name()
+    {
+        // arrange
+        var metadata = new ApiVersionMetadata( ApiVersionModel.Empty, new ApiVersionModel( ApiVersion.Default ) );
+        var descriptor = new ActionDescriptor() { EndpointMetadata = new[] { metadata } };
+        var actionProvider = new TestActionDescriptorCollectionProvider( descriptor );
+        var context = new ApiDescriptionProviderContext( actionProvider.ActionDescriptors.Items );
+        var apiExplorer = new VersionedApiDescriptionProvider(
+            Mock.Of<ISunsetPolicyManager>(),
+            NewModelMetadataProvider(),
+            Options.Create( new ApiExplorerOptions() ) );
+
+        context.Results.Add( new()
+        {
+            ActionDescriptor = descriptor,
+            GroupName = "Test",
+        } );
+
+        // act
+        apiExplorer.OnProvidersExecuted( context );
+
+        // assert
+        context.Results.Single().GroupName.Should().Be( "Test" );
+    }
+
+    [Fact]
+    public void versioned_api_explorer_should_use_custom_group_name()
+    {
+        // arrange
+        var metadata = new ApiVersionMetadata( ApiVersionModel.Empty, new ApiVersionModel( ApiVersion.Default ) );
+        var descriptor = new ActionDescriptor() { EndpointMetadata = new[] { metadata } };
+        var actionProvider = new TestActionDescriptorCollectionProvider( descriptor );
+        var context = new ApiDescriptionProviderContext( actionProvider.ActionDescriptors.Items );
+        var options = new ApiExplorerOptions()
+        {
+            FormatGroupName = ( group, version ) => $"{group}-{version}",
+        };
+        var apiExplorer = new VersionedApiDescriptionProvider(
+            Mock.Of<ISunsetPolicyManager>(),
+            NewModelMetadataProvider(),
+            Options.Create( options ) );
+
+        context.Results.Add( new()
+        {
+            ActionDescriptor = descriptor,
+            GroupName = "Test",
+        } );
+
+        // act
+        apiExplorer.OnProvidersExecuted( context );
+
+        // assert
+        context.Results.Single().GroupName.Should().Be( "Test-1.0" );
+    }
+
     private static IModelMetadataProvider NewModelMetadataProvider()
     {
         var provider = new Mock<IModelMetadataProvider>();