Fix OpenTelemetry legacy trace

lib/graphql/schema.rb

@@ -170,9 +170,9 @@ def trace_class(new_class = nil)
       end
 
       # @return [Class] Return the trace class to use for this mode, looking one up on the superclass if this Schema doesn't have one defined.
-      def trace_class_for(mode, build: false)
+      def trace_class_for(mode)
         own_trace_modes[mode] ||
-          (superclass.respond_to?(:trace_class_for) ? superclass.trace_class_for(mode) : nil)
+          (superclass.respond_to?(:trace_class_for) ? superclass.trace_class_for(mode) : (own_trace_modes[mode] = build_trace_mode(mode)))
       end
 
       # Configure `trace_class` to be used whenever `context: { trace_mode: mode_name }` is requested.
@@ -921,7 +921,6 @@ def resolve_type(type, obj, ctx)
 
       def inherited(child_class)
         if self == GraphQL::Schema
-          child_class.own_trace_modes[:default] = child_class.build_trace_mode(:default)
           child_class.directives(default_directives.values)
         end
         # Make sure the child class has these built out, so that

spec/graphql/tracing/legacy_trace_spec.rb

@@ -48,6 +48,7 @@ def self.trace(key, data)
     custom_trace_module = Module.new do
       def execute_query(query:)
         query.context[:trace_module_ran] = true
+        super
       end
     end
 
@@ -69,13 +70,12 @@ def int
       tracer(custom_tracer)
     end
 
-
     res1 = parent_schema.execute("{ int }")
     assert_equal true, res1.context[:trace_module_ran]
     assert_nil res1.context[:tracer_ran]
 
     res2 = child_schema.execute("{ int }")
-    assert_equal true, res2.context[:trace_module_ran]
-    assert_equal true, res2.context[:tracer_ran]
+    assert_equal true, res2.context[:trace_module_ran], "New Trace Ran"
+    assert_equal true, res2.context[:tracer_ran], "Legacy Trace Ran"
   end
 end

spec/graphql/tracing/trace_modes_spec.rb

@@ -110,6 +110,34 @@ def execute_query(query:)
     assert_equal :was_configured, res.context[:configured_option]
   end
 
+  describe "inheriting from GraphQL::Schema" do
+    it "gets CallLegacyTracers" do
+      # Use a new base trace mode class to avoid polluting the base class
+      # which already-initialized schemas have in their inheritance chain
+      # (It causes `CallLegacyTracers` to end up in the chain twice otherwise)
+      GraphQL::Schema.own_trace_modes[:default] = GraphQL::Schema.build_trace_mode(:default)
+
+      child_class = Class.new(GraphQL::Schema)
+
+      # Initialize the trace class, make sure no legacy tracers are present at this point:
+      refute_includes child_class.trace_class_for(:default).ancestors, GraphQL::Tracing::CallLegacyTracers
+      tracer_class = Class.new
+
+      # add a legacy tracer
+      GraphQL::Schema.tracer(tracer_class)
+      # A newly created child class gets the right setup:
+      new_child_class = Class.new(GraphQL::Schema)
+      assert_includes new_child_class.trace_class_for(:default).ancestors, GraphQL::Tracing::CallLegacyTracers
+      # But what about an already-created child class?
+      assert_includes child_class.trace_class_for(:default).ancestors, GraphQL::Tracing::CallLegacyTracers
+
+      # Reset GraphQL::Schema tracer state:
+      GraphQL::Schema.send(:own_tracers).delete(tracer_class)
+      GraphQL::Schema.own_trace_modes[:default] = GraphQL::Schema.build_trace_mode(:default)
+      refute_includes GraphQL::Schema.new_trace.class.ancestors, GraphQL::Tracing::CallLegacyTracers
+    end
+  end
+
 
   describe "custom default trace mode" do
     class CustomDefaultSchema < TraceModesTest::ParentSchema