Updates based on code review feedback

src/VisualStudio/Core/Test.Next/Mocks/TestOptionSet.cs

@@ -33,7 +33,7 @@ public override OptionSet WithChangedOption(OptionKey optionAndLanguage, object
             return new TestOptionSet(_values.SetItem(optionAndLanguage, value));
         }
 
-        internal virtual IEnumerable<OptionKey> GetChangedOptions(OptionSet optionSet)
+        public virtual IEnumerable<OptionKey> GetChangedOptions(OptionSet optionSet)
         {
             foreach (var kvp in _values)
             {
@@ -44,10 +44,5 @@ internal virtual IEnumerable<OptionKey> GetChangedOptions(OptionSet optionSet)
                 }
             }
         }
-
-        IEnumerable<OptionKey> IInternalOptionSet.GetChangedOptions(OptionSet optionSet)
-        {
-            return GetChangedOptions(optionSet);
-        }
     }
 }

src/VisualStudio/Core/Test.Next/Services/SolutionServiceTests.cs

@@ -110,9 +110,8 @@ public async Task TestCreationWithOption()
 
                 Assert.Equal(solutionChecksum, await synched.State.GetChecksumAsync(CancellationToken.None));
 
-                var internalOptions = options as IInternalOptionSet;
-                Assert.NotNull(internalOptions);
-                Assert.Empty(internalOptions.GetChangedOptions(synched.Workspace.Options));
+                Assert.IsAssignableFrom<IInternalOptionSet>(options);
+                Assert.Empty(((IInternalOptionSet)options).GetChangedOptions(synched.Workspace.Options));
 
                 Assert.True(options.GetOption(RemoteHostOptions.RemoteHostTest));
                 Assert.True(synched.Workspace.Options.GetOption(RemoteHostOptions.RemoteHostTest));

src/Workspaces/CoreTest/Execution/SnapshotSerializationTests.cs

@@ -637,9 +637,8 @@ private static async Task VerifyOptionSetsAsync(Workspace workspace, string lang
                     Assert.Equal(asset.Checksum, assetFromStorage.Checksum);
 
                     // option should be exactly same
-                    var internalRecovered = recovered as IInternalOptionSet;
-                    Assert.NotNull(internalRecovered);
-                    Assert.Equal(0, internalRecovered.GetChangedOptions(workspace.Options).Count());
+                    Assert.IsAssignableFrom<IInternalOptionSet>(recovered);
+                    Assert.Equal(0, ((IInternalOptionSet)recovered).GetChangedOptions(workspace.Options).Count());
                 }
             }
         }