Immediately return empty array in multiplex if queries list is empty

Author: ilyasgaraev

lib/graphql/execution/interpreter.rb

@@ -33,6 +33,7 @@ def run_all(schema, query_options, context: {}, max_complexity: schema.max_compl
             end
           end
 
+          return GraphQL::EmptyObjects::EMPTY_ARRAY if queries.empty?
 
           multiplex = Execution::Multiplex.new(schema: schema, queries: queries, context: context, max_complexity: max_complexity)
           Fiber[:__graphql_current_multiplex] = multiplex

spec/graphql/execution/interpreter_spec.rb

@@ -949,4 +949,25 @@ def variant
       assert_equal(expected_result, res["data"])
     end
   end
+
+  describe "multiplex queries" do
+    it "runs multiplex queries" do
+      result = InterpreterTest::Schema.multiplex([
+        {
+          query: "query Card($name: String!) { card(name: $name) { colors } }",
+          variables: { name: "Dark Confidant" },
+          operation_name: "Card"
+        },
+        {
+          query: "query Expansion($expansion: String!) { expansion(sym: $expansion) { cards { name } } }",
+          variables: { expansion: "RAV" },
+          operation_name: "Expansion"
+        }
+      ])
+
+      assert_equal ["BLACK"], result[0]["data"]["card"]["colors"]
+      assert_equal [{"name" => "Dark Confidant"}], result[1]["data"]["expansion"]["cards"]
+      assert_nil Fiber[:__graphql_runtime_info]
+    end
+  end
 end

spec/graphql/tracing/new_relic_trace_spec.rb

@@ -237,4 +237,29 @@ class SchemaWithoutAuthorizedOrResolveType < GraphQL::Schema
     ]
     assert_equal expected_steps, NewRelic::EXECUTION_SCOPES
   end
+
+  describe "multiplex queries" do
+    it "handles multiplex" do
+      NewRelicTraceTest::SchemaWithTransactionName.multiplex([
+        {
+          query: "query Q1 { int }",
+          variables: {},
+          operation_name: "Q1"
+        },
+        {
+          query: "query Q2 { int }",
+          variables: {},
+          operation_name: "Q2"
+        }
+      ])
+
+      assert_equal ["GraphQL/query.Q1"], NewRelic::TRANSACTION_NAMES
+    end
+
+    it "handles empty multiplex" do
+      NewRelicTraceTest::SchemaWithTransactionName.multiplex([])
+
+      assert_equal [], NewRelic::TRANSACTION_NAMES
+    end
+  end
 end