Ensure we respond to requests with IDs or client will hang

lib/standard/lsp/routes.rb

@@ -122,6 +122,12 @@ def handle_unsupported_method(request, method = request[:method])
         @logger.puts "Unsupported Method: #{method}"
       end
 
+      def handle_method_missing(request)
+        if request.key?(:id)
+          @writer.write({id: request[:id], result: nil})
+        end
+      end
+
       private
 
       def format_file(file_uri)

lib/standard/lsp/server.rb

@@ -23,10 +23,9 @@ def initialize(standardizer)
 
       def start
         @reader.read do |request|
-          next unless request.key?(:method) # ignore responses without methods
-
-          method = request[:method]
-          if (route = @routes.for(method))
+          if !request.key?(:method)
+            @routes.handle_method_missing(request)
+          elsif (route = @routes.for(request[:method]))
             route.call(request)
           else
             @routes.handle_unsupported_method(request)

test/standard/runners/lsp_test.rb

@@ -270,7 +270,7 @@ def test_unknown_commands
     }, msgs.last)
   end
 
-  def test_methodless_requests_are_ignored
+  def test_methodless_requests_are_acked
     msgs, err = run_server_on_requests(
       {
         id: 1,
@@ -279,6 +279,22 @@ def test_methodless_requests_are_ignored
       }
     )
 
+    assert_equal "", err.string
+    assert_equal({
+      id: 1,
+      jsonrpc: "2.0",
+      result: nil
+    }, msgs.last)
+  end
+
+  def test_methodless_and_idless_requests_are_dropped
+    msgs, err = run_server_on_requests(
+      {
+        jsonrpc: "2.0",
+        result: {}
+      }
+    )
+
     assert_equal "", err.string
     assert_empty msgs
   end