Finish tests.

src/Workspaces/SharedUtilitiesAndExtensions/Workspace/Core/Extensions/SyntaxGeneratorExtensions.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Generic;
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.Editing;
 using Roslyn.Utilities;
@@ -58,10 +59,11 @@ private static SyntaxNode CreateNotImplementedException(SyntaxGenerator codeDefi
             ITypeSymbol type)
         {
             var equalityComparerType = compilation.EqualityComparerOfTType();
-            var constructedType = equalityComparerType.Construct(type);
-            return factory.MemberAccessExpression(
-                factory.TypeExpression(constructedType),
-                factory.IdentifierName(DefaultName));
+            var typeExpression = equalityComparerType == null
+                ? factory.GenericName(nameof(EqualityComparer<int>), type)
+                : factory.TypeExpression(equalityComparerType.Construct(type));
+
+            return factory.MemberAccessExpression(typeExpression, factory.IdentifierName(DefaultName));
         }
 
         private static ITypeSymbol GetType(Compilation compilation, ISymbol symbol)