refactor unimplemented directive handling

codegen/directives.gotpl

@@ -14,6 +14,9 @@
 						}
 					{{- end }}
 			{{- end }}
+			if ec.directives.{{$directive.Name|ucFirst}} == nil {
+				return nil, errors.New("directive {{$directive.Name}} is not implemented")
+			}
 			return ec.directives.{{$directive.Name|ucFirst}}({{$directive.ResolveArgs $in $i }})
 		}
 	{{ end -}}
@@ -34,6 +37,9 @@
 			{{- end }}
 			n := next
 			next = func(ctx context.Context) (interface{}, error) {
+				if ec.directives.{{$directive.Name|ucFirst}} == nil {
+					return nil, errors.New("directive {{$directive.Name}} is not implemented")
+				}
 				return ec.directives.{{$directive.Name|ucFirst}}({{$directive.CallArgs}})
 			}
 		{{- end }}
@@ -81,6 +87,9 @@ func (ec *executionContext) _subscriptionMiddleware(ctx context.Context, obj *as
 			{{- end }}
 			n := next
 			next = func(ctx context.Context) (interface{}, error) {
+				if ec.directives.{{$directive.Name|ucFirst}} == nil {
+					return nil, errors.New("directive {{$directive.Name}} is not implemented")
+				}
 				return ec.directives.{{$directive.Name|ucFirst}}({{$directive.CallArgs}})
 			}
 		{{- end }}
@@ -121,6 +130,9 @@ func (ec *executionContext) _subscriptionMiddleware(ctx context.Context, obj *as
 				{{- end }}
 				n := next
 				next = func(ctx context.Context) (interface{}, error) {
+					if ec.directives.{{$directive.Name|ucFirst}} == nil {
+						return nil, errors.New("directive {{$directive.Name}} is not implemented")
+					}
 					return ec.directives.{{$directive.Name|ucFirst}}({{$directive.CallArgs}})
 				}
 			{{- end }}

codegen/testserver/directive.graphql

@@ -5,6 +5,7 @@ directive @logged(id: UUID!) on FIELD
 directive @toNull on ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION | FIELD_DEFINITION
 directive @directive1 on FIELD_DEFINITION
 directive @directive2 on FIELD_DEFINITION
+directive @unimplemented on FIELD_DEFINITION
 
 extend type Query {
     directiveArg(arg: String! @length(min:1, max: 255, message: "invalid length")): String
@@ -16,6 +17,7 @@ extend type Query {
     directiveFieldDef(ret: String!): String! @length(min: 1, message: "not valid")
     directiveField: String
     directiveDouble: String @directive1 @directive2
+    directiveUnimplemented: String @unimplemented
 }
 
 input InputDirectives {

codegen/testserver/directive_test.go

@@ -60,6 +60,11 @@ func TestDirectives(t *testing.T) {
 		return &s, nil
 	}
 
+	resolvers.QueryResolver.DirectiveUnimplemented = func(ctx context.Context) (*string, error) {
+		s := "Ok"
+		return &s, nil
+	}
+
 	srv := httptest.NewServer(
 		handler.GraphQL(
 			NewExecutableSchema(Config{
@@ -137,6 +142,7 @@ func TestDirectives(t *testing.T) {
 					Directive2: func(ctx context.Context, obj interface{}, next graphql.Resolver) (res interface{}, err error) {
 						return next(ctx)
 					},
+					Unimplemented: nil,
 				},
 			}),
 			handler.ResolverMiddleware(func(ctx context.Context, next graphql.Resolver) (res interface{}, err error) {
@@ -227,6 +233,16 @@ func TestDirectives(t *testing.T) {
 			require.Equal(t, "Ok", resp.DirectiveDouble)
 		})
 
+		t.Run("directive is not implemented", func(t *testing.T) {
+			var resp struct {
+				DirectiveUnimplemented string
+			}
+
+			err := c.Post(`query { directiveUnimplemented }`, &resp)
+
+			require.EqualError(t, err, `[{"message":"directive unimplemented is not implemented","path":["directiveUnimplemented"]}]`)
+		})
+
 		t.Run("ok", func(t *testing.T) {
 			var resp struct {
 				DirectiveFieldDef string

codegen/testserver/resolver.go

@@ -176,6 +176,9 @@ func (r *queryResolver) DirectiveField(ctx context.Context) (*string, error) {
 func (r *queryResolver) DirectiveDouble(ctx context.Context) (*string, error) {
 	panic("not implemented")
 }
+func (r *queryResolver) DirectiveUnimplemented(ctx context.Context) (*string, error) {
+	panic("not implemented")
+}
 func (r *queryResolver) MapStringInterface(ctx context.Context, in map[string]interface{}) (map[string]interface{}, error) {
 	panic("not implemented")
 }