Fix failing tests.

Author: bjorkstromm

src/Protocol/Models/DocumentSelector.cs

@@ -39,7 +39,9 @@ public static implicit operator DocumentSelector(List<DocumentFilter> items)
 
         public static implicit operator string(DocumentSelector documentSelector)
         {
-            return string.Join(", ", documentSelector.Select(x => (string)x));
+            return documentSelector != null ?
+                string.Join(", ", documentSelector.Select(x => (string)x)) :
+                null;
         }
 
         public bool IsMatch(TextDocumentAttributes attributes)

src/Server/Matchers/ResolveCommandMatcher.cs

@@ -127,10 +127,8 @@ public object Process(ILspHandlerDescriptor descriptor, object parameters)
 
         public object Process(ILspHandlerDescriptor descriptor, object parameters, object response)
         {
-            var registrationOptions = descriptor.Registration.RegisterOptions as TextDocumentRegistrationOptions;
-
             // Only pin the handler type, if we know the source handler (codelens) is also the resolver.
-            if (registrationOptions?.DocumentSelector != null &&
+            if (descriptor is HandlerDescriptor handlerDescriptor &&
                 response is IEnumerable<ICanBeResolved> canBeResolveds &&
                 descriptor?.CanBeResolvedHandlerType?.GetTypeInfo().IsAssignableFrom(descriptor.Handler.GetType()) == true)
             {
@@ -145,7 +143,7 @@ response is IEnumerable<ICanBeResolved> canBeResolveds &&
                     var data = new JObject();
                     data["data"] = item.Data;
                     data[PrivateHandlerTypeName] = descriptor.Handler.GetType().FullName;
-                    data[PrivateHandlerKey] = registrationOptions.DocumentSelector.ToString();
+                    data[PrivateHandlerKey] = handlerDescriptor.Key;
                     item.Data = data;
                 }
             }

test/Lsp.Tests/Matchers/ResolveCommandMatcherTests.cs

@@ -374,6 +374,7 @@ public void Should_Update_CompletionItems_With_HandlerType()
             (response as CompletionList).Items.Should().Contain(item);
             var responseItem = (response as CompletionList).Items.First();
             responseItem.Data[ResolveCommandMatcher.PrivateHandlerTypeName].Value<string>().Should().NotBeNullOrEmpty();
+            responseItem.Data[ResolveCommandMatcher.PrivateHandlerKey].Value<string>().Should().NotBeNullOrEmpty();
             responseItem.Data["data"]["hello"].Value<string>().Should().Be("world");
         }
 
@@ -412,6 +413,7 @@ public void Should_Update_CodeLensContainer_With_HandlerType()
             (response as CodeLensContainer).Should().Contain(item);
             var responseItem = (response as CodeLensContainer).First();
             responseItem.Data[ResolveCommandMatcher.PrivateHandlerTypeName].Value<string>().Should().NotBeNullOrEmpty();
+            responseItem.Data[ResolveCommandMatcher.PrivateHandlerKey].Value<string>().Should().NotBeNullOrEmpty();
             responseItem.Data["data"]["hello"].Value<string>().Should().Be("world");
         }