Add test

src/EditorFeatures/TestUtilities/ChangeSignature/TestChangeSignatureOptionsService.cs

@@ -6,7 +6,6 @@
 using System.Linq;
 using Microsoft.CodeAnalysis.ChangeSignature;
 using Microsoft.CodeAnalysis.Host.Mef;
-using Microsoft.CodeAnalysis.Notification;
 
 namespace Microsoft.CodeAnalysis.Editor.UnitTests.ChangeSignature
 {
@@ -21,7 +20,7 @@ public TestChangeSignatureOptionsService()
         {
         }
 
-        public ChangeSignatureOptionsResult GetChangeSignatureOptions(ISymbol symbol, ParameterConfiguration parameters, INotificationService notificationService)
+        public ChangeSignatureOptionsResult GetChangeSignatureOptions(ISymbol symbol, ParameterConfiguration parameters)
         {
             var list = parameters.ToListOfParameters();
 

src/VisualStudio/Core/Def/Implementation/ChangeSignature/ChangeSignatureDialogViewModel.cs

@@ -11,7 +11,6 @@
 using Microsoft.CodeAnalysis.ChangeSignature;
 using Microsoft.CodeAnalysis.Editor.Shared.Extensions;
 using Microsoft.CodeAnalysis.Editor.Shared.Utilities;
-using Microsoft.CodeAnalysis.Notification;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Utilities;
 using Microsoft.VisualStudio.Text.Classification;
 using Roslyn.Utilities;

src/VisualStudio/Core/Test/ChangeSignature/ChangeSignatureViewModelTests.vb

@@ -8,7 +8,6 @@ Imports Microsoft.CodeAnalysis
 Imports Microsoft.CodeAnalysis.ChangeSignature
 Imports Microsoft.CodeAnalysis.Editor.Shared.Utilities
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Extensions
-Imports Microsoft.CodeAnalysis.Editor.UnitTests.Utilities
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces
 Imports Microsoft.CodeAnalysis.LanguageServices
 Imports Microsoft.CodeAnalysis.Shared.Extensions
@@ -260,6 +259,33 @@ class MyClass
                 type:="string?")
         End Function
 
+        <Fact, Trait(Traits.Feature, Traits.Features.ChangeSignature)>
+        <WorkItem(30315, "https://github.com/dotnet/roslyn/issues/30315")>
+        Public Async Function ChangeSignature_ParameterDisplay_DefaultStruct() As Tasks.Task
+            Dim markup = <Text><![CDATA[
+struct MyStruct
+{
+
+}
+
+class Goo
+{
+    void $$Bar(MyStruct s = default(MyStruct))
+    {
+
+    }
+}"]]></Text>
+
+            Dim viewModelTestState = Await GetViewModelTestStateAsync(markup, LanguageNames.CSharp)
+            Dim viewModel = viewModelTestState.ViewModel
+            VerifyOpeningState(viewModel, "private void Bar(MyStruct s = default(MyStruct))")
+            VerifyParameterInfo(
+                viewModel,
+                parameterIndex:=0,
+                type:="MyStruct",
+                defaultValue:="default")
+        End Function
+
         Private Sub VerifyAlteredState(
            viewModelTestState As ChangeSignatureViewModelTestState,
            Optional monitor As PropertyChangedTestMonitor = Nothing,
@@ -352,8 +378,6 @@ class MyClass
             If needsBottomBorder.HasValue Then
                 Assert.Equal(needsBottomBorder.Value, parameter.NeedsBottomBorder)
             End If
-
-
         End Sub
 
         Private Async Function GetViewModelTestStateAsync(
@@ -379,7 +403,6 @@ class MyClass
                 Dim symbol = (Await workspaceDoc.GetSemanticModelAsync()).GetDeclaredSymbol(token.Parent)
 
                 Dim viewModel = New ChangeSignatureDialogViewModel(
-                    New TestNotificationService(),
                     ParameterConfiguration.Create(symbol.GetParameters().ToList(), symbol.IsExtensionMethod(), selectedIndex:=0),
                     symbol,
                     workspace.ExportProvider.GetExportedValue(Of IClassificationFormatMapService)().GetClassificationFormatMap("text"),