Improve enum value (with vars) validation timing

codegen/testserver/enum.graphql

@@ -0,0 +1,12 @@
+enum EnumTest {
+    OK
+    NG
+}
+
+input InputWithEnumValue {
+    enum: EnumTest!
+}
+
+extend type Query {
+    enumInInput(input: InputWithEnumValue): EnumTest!
+}

codegen/testserver/enums_test.go

@@ -0,0 +1,52 @@
+package testserver
+
+import (
+	"context"
+	"testing"
+
+	"github.com/99designs/gqlgen/client"
+	"github.com/99designs/gqlgen/handler"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEnumsResolver(t *testing.T) {
+	resolvers := &Stub{}
+	resolvers.QueryResolver.EnumInInput = func(ctx context.Context, input *InputWithEnumValue) (EnumTest, error) {
+		return input.Enum, nil
+	}
+
+	c := client.New(handler.GraphQL(NewExecutableSchema(Config{Resolvers: resolvers})))
+
+	t.Run("input with valid enum value", func(t *testing.T) {
+		var resp struct {
+			EnumInInput EnumTest
+		}
+		c.MustPost(`query {
+			enumInInput(input: {enum: OK})
+		}
+		`, &resp)
+		require.Equal(t, resp.EnumInInput, EnumTestOk)
+	})
+
+	t.Run("input with invalid enum value", func(t *testing.T) {
+		var resp struct {
+			EnumInInput EnumTest
+		}
+		err := c.Post(`query {
+			enumInInput(input: {enum: INVALID})
+		}
+		`, &resp)
+		require.EqualError(t, err, `http 422: {"errors":[{"message":"Expected type EnumTest!, found INVALID.","locations":[{"line":2,"column":30}]}],"data":null}`)
+	})
+
+	t.Run("input with invalid enum value via vars", func(t *testing.T) {
+		var resp struct {
+			EnumInInput EnumTest
+		}
+		err := c.Post(`query ($input: InputWithEnumValue) {
+			enumInInput(input: $input)
+		}
+		`, &resp, client.Var("input", map[string]interface{}{"enum": "INVALID"}))
+		require.EqualError(t, err, `http 422: {"errors":[{"message":"INVALID is not a valid EnumTest","path":["variable","input","enum"]}],"data":null}`)
+	})
+}

codegen/testserver/generated_test.go

@@ -31,6 +31,11 @@ func TestEnums(t *testing.T) {
 		require.Equal(t, StatusOk, AllStatus[0])
 		require.Equal(t, StatusError, AllStatus[1])
 	})
+
+	t.Run("invalid enum values", func(t *testing.T) {
+		require.Equal(t, StatusOk, AllStatus[0])
+		require.Equal(t, StatusError, AllStatus[1])
+	})
 }
 
 func TestUnionFragments(t *testing.T) {

codegen/testserver/resolver.go

@@ -188,6 +188,9 @@ func (r *queryResolver) EmbeddedCase2(ctx context.Context) (*EmbeddedCase2, erro
 func (r *queryResolver) EmbeddedCase3(ctx context.Context) (*EmbeddedCase3, error) {
 	panic("not implemented")
 }
+func (r *queryResolver) EnumInInput(ctx context.Context, input *InputWithEnumValue) (EnumTest, error) {
+	panic("not implemented")
+}
 func (r *queryResolver) Shapes(ctx context.Context) ([]Shape, error) {
 	panic("not implemented")
 }