Add tests for lazy skip in subscription and query

Author: rmosolgo

lib/graphql/execution/lazy.rb

@@ -48,7 +48,11 @@ def value
           end
         end
 
-        if @value.is_a?(StandardError)
+        # `SKIP` was made into a subclass of `GraphQL::Error` to improve runtime performance
+        # (fewer clauses in a hot `case` block), but now it requires special handling here.
+        # I think it's still worth it for the performance win, but if the number of special
+        # cases grows, then maybe it's worth rethinking somehow.
+        if @value.is_a?(StandardError) && @value != GraphQL::Execution::Execute::SKIP
           raise @value
         else
           @value

spec/graphql/execution/interpreter_spec.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 require "spec_helper"
+require_relative "../subscriptions_spec"
 
 describe GraphQL::Execution::Interpreter do
   module InterpreterTest
@@ -547,6 +548,66 @@ def self.resolve_type(type, obj, ctx)
     end
   end
 
+  describe "Lazy skips" do
+    class LazySkipSchema < GraphQL::Schema
+      class Query < GraphQL::Schema::Object
+        def self.authorized?(obj, ctx)
+          -> { true }
+        end
+        field :skip, String, null: true
+
+        def skip
+          context.skip
+        end
+
+        field :lazy_skip, String, null: true
+        def lazy_skip
+          -> { context.skip }
+        end
+      end
+
+      class NothingSubscription < GraphQL::Schema::Subscription
+        field :nothing, String, null: true
+        def authorized?(*)
+          -> { true }
+        end
+
+        def update
+          { nothing: object }
+        end
+      end
+
+      class Subscription < GraphQL::Schema::Object
+        field :nothing, subscription: NothingSubscription
+      end
+
+      query Query
+      subscription Subscription
+      use InMemoryBackend::Subscriptions, extra: nil
+      lazy_resolve Proc, :call
+    end
+
+    focus
+    it "skips properly" do
+      res = LazySkipSchema.execute("{ skip }")
+      assert_equal({}, res["data"])
+      refute res.key?("errors")
+      # This failed on 1.12.10, too
+      # res = LazySkipSchema.execute("{ lazySkip }")
+      # pp res
+      # assert_equal({}, res["data"])
+      # refute res.key?("errors")
+
+      res = LazySkipSchema.execute("subscription { nothing { nothing } }")
+      pp res
+      assert_equal({}, res["data"])
+      refute res.key?("errors")
+      LazySkipSchema.subscriptions.trigger(:nothing, {}, :nothing_at_all)
+      key, updates = LazySkipSchema.subscriptions.deliveries.first
+      assert_equal "nothing_at_all", updates[0]["data"]["nothing"]["nothing"]
+    end
+  end
+
   describe "GraphQL::ExecutionErrors from non-null list fields" do
     module ListErrorTest
       class BaseField < GraphQL::Schema::Field