Add Designer/runtime layout parity test suite

ModernFormsNext.CodeGeneration/CSharp/CSharpDesignerGenerator.cs

@@ -151,7 +151,8 @@ public CSharpDesignerGenerationResult Generate(
         if (document.RootKind == DesignRootKind.Form)
             writer.WriteLine($"        this.Text = {CSharpLiteralWriter.WriteStringLiteral(rootName)};");
 
-        writer.WriteLine($"        this.Size = new System.Drawing.Size({document.Size.Width}, {document.Size.Height});");
+        var rootSizeProperty = document.RootKind == DesignRootKind.Form ? "ClientSize" : "Size";
+        writer.WriteLine($"        this.{rootSizeProperty} = new System.Drawing.Size({document.Size.Width}, {document.Size.Height});");
 
         foreach (var property in document.Properties)
         {

ModernFormsNext.CodeGeneration/Reverse/CSharpDesignerParser.cs

@@ -652,9 +652,8 @@ private void ProcessFormPropertyAssignment(
 
                 break;
 
-            // Size is the canonical generated contract. Keep accepting ClientSize from earlier
-            // designer builds so existing .Designer.cs files can still be imported and rewritten
-            // in the current canonical form.
+            // Form documents canonically use ClientSize while UserControl documents use Size.
+            // Accept both spellings so older generated files remain importable.
             case "Size":
             case "ClientSize":
                 if (TryReadSize(valueExpression, out var width, out var height))
@@ -1052,6 +1051,17 @@ private static bool TryReadDouble(ExpressionSyntax expression, out double value)
 
     private static bool TryReadEnum(ExpressionSyntax expression, out string enumTypeName, out string memberName)
     {
+        if (expression is BinaryExpressionSyntax binary
+            && binary.IsKind(SyntaxKind.BitwiseOrExpression)
+            && TryReadEnum(binary.Left, out var leftTypeName, out var leftMemberName)
+            && TryReadEnum(binary.Right, out var rightTypeName, out var rightMemberName)
+            && string.Equals(leftTypeName, rightTypeName, StringComparison.Ordinal))
+        {
+            enumTypeName = leftTypeName;
+            memberName = $"{leftMemberName}, {rightMemberName}";
+            return true;
+        }
+
         if (expression is MemberAccessExpressionSyntax memberAccess)
         {
             enumTypeName = memberAccess.Expression.ToString();

ModernFormsNext.Designer.Tests/CSharpDesignerRoundTripTests.cs

@@ -8,7 +8,7 @@ namespace ModernFormsNext.Designer.Tests;
 public sealed class CSharpDesignerRoundTripTests
 {
     [Fact]
-    public void GeneratorUsesSizeAndNeverEmitsClientSize()
+    public void FormGeneratorUsesClientSizeAndNeverEmitsOuterSize()
     {
         var document = CreateDocument();
         document.Properties["Size"] = DesignPropertyValue.FromInt32(456);
@@ -17,8 +17,8 @@ public void GeneratorUsesSizeAndNeverEmitsClientSize()
         var result = new CSharpDesignerGenerator().Generate(document);
 
         Assert.True(result.Succeeded, string.Join(Environment.NewLine, result.Validation.Errors));
-        Assert.Contains("this.Size = new System.Drawing.Size(900, 600);", result.Code);
-        Assert.DoesNotContain("this.ClientSize =", result.Code);
+        Assert.Contains("this.ClientSize = new System.Drawing.Size(900, 600);", result.Code);
+        Assert.DoesNotContain("this.Size =", result.Code);
     }
 
     [Theory]
@@ -61,8 +61,8 @@ public void RepeatedMfdesignAndCodeRoundTripsKeepLogicalGeometry()
             document = serializer.Deserialize(serializer.Serialize(document));
             var generated = service.Generate(document);
             Assert.True(generated.Succeeded, string.Join(Environment.NewLine, generated.Validation.Errors));
-            Assert.Contains("this.Size = new System.Drawing.Size(900, 600);", generated.Code);
-            Assert.DoesNotContain("this.ClientSize =", generated.Code);
+            Assert.Contains("this.ClientSize = new System.Drawing.Size(900, 600);", generated.Code);
+            Assert.DoesNotContain("this.Size =", generated.Code);
 
             var parsed = service.ParseDesignerCode(generated.Code);
             Assert.True(parsed.Success, string.Join(Environment.NewLine, parsed.Diagnostics.Select(diagnostic => diagnostic.Message)));