Add invalid null error for mutations

Author: rmosolgo

lib/graphql.rb

@@ -91,13 +91,13 @@ def -@
 require "graphql/tracing"
 require "graphql/dig"
 require "graphql/execution"
+require "graphql/runtime_type_error"
+require "graphql/unresolved_type_error"
+require "graphql/invalid_null_error"
 require "graphql/schema"
 require "graphql/query"
 require "graphql/directive"
 require "graphql/execution"
-require "graphql/runtime_type_error"
-require "graphql/unresolved_type_error"
-require "graphql/invalid_null_error"
 require "graphql/types"
 require "graphql/relay"
 require "graphql/boolean_type"

lib/graphql/schema/member.rb

@@ -4,6 +4,7 @@
 require 'graphql/schema/member/cached_graphql_definition'
 require 'graphql/schema/member/graphql_type_names'
 require 'graphql/schema/member/has_ast_node'
+require 'graphql/schema/member/has_invalid_null_error'
 require 'graphql/schema/member/has_path'
 require 'graphql/schema/member/has_unresolved_type_error'
 require 'graphql/schema/member/relay_shortcuts'

lib/graphql/schema/member/has_invalid_null_error.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module GraphQL
+  class Schema
+    class Member
+      module HasInvalidNullError
+        # Set up a member-specific invalid null error
+        # to use when this member's non-null fields wrongly return `nil`.
+        # It should help with debugging and bug tracker integrations.
+        def inherited(child_class)
+          child_class.const_set(:InvalidNullError, Class.new(GraphQL::InvalidNullError))
+          super
+        end
+      end
+    end
+  end
+end

lib/graphql/schema/mutation.rb

@@ -60,6 +60,7 @@ class Schema
     #
     class Mutation < GraphQL::Schema::Resolver
       extend GraphQL::Schema::Member::HasFields
+      extend GraphQL::Schema::Member::HasInvalidNullError
       extend GraphQL::Schema::Resolver::HasPayloadType
 
       class << self

lib/graphql/schema/object.rb

@@ -7,6 +7,7 @@ class Schema
     class Object < GraphQL::Schema::Member
       extend GraphQL::Schema::Member::AcceptsDefinition
       extend GraphQL::Schema::Member::HasFields
+      extend GraphQL::Schema::Member::HasInvalidNullError
 
       # @return [Object] the application object this type is wrapping
       attr_reader :object
@@ -71,13 +72,6 @@ def initialize(object, context)
       end
 
       class << self
-        # Set up a type-specific invalid null error to use when this object's non-null fields wrongly return `nil`.
-        # It should help with debugging and bug tracker integrations.
-        def inherited(child_class)
-          child_class.const_set(:InvalidNullError, Class.new(GraphQL::InvalidNullError))
-          super
-        end
-
         def implements(*new_interfaces, **options)
           new_memberships = []
           new_interfaces.each do |int|

spec/graphql/schema/mutation_spec.rb

@@ -113,6 +113,13 @@
       response = Jazz::Schema.execute(query_str)
       assert_equal 2, response["errors"].length, "It should return two errors"
     end
+
+    it "raises a mutation-specific invalid null error" do
+      query_str = "mutation { returnInvalidNull { int } }"
+      response = Jazz::Schema.execute(query_str)
+      assert_equal ["Cannot return null for non-nullable field ReturnInvalidNull.int"], response["errors"].map { |e| e["message"] }
+      assert_instance_of Jazz::ReturnInvalidNull::InvalidNullError, response.query.context.errors.first
+    end
   end
 
   describe ".null" do

spec/support/jazz.rb

@@ -776,6 +776,14 @@ def resolve
     end
   end
 
+  class ReturnInvalidNull < GraphQL::Schema::Mutation
+    field :int, Integer, null: false
+
+    def resolve
+      { int: nil }
+    end
+  end
+
   class Mutation < BaseObject
     field :add_ensemble, Ensemble, null: false do
       argument :input, EnsembleInput, required: true
@@ -796,6 +804,7 @@ class Mutation < BaseObject
     field :has_extras, mutation: HasExtras
     field :has_extras_stripped, mutation: HasExtrasStripped
     field :has_field_extras, mutation: HasFieldExtras, extras: [:lookahead]
+    field :return_invalid_null, mutation: ReturnInvalidNull
 
     def add_ensemble(input:)
       ens = Models::Ensemble.new(input.name)