Ignore __ fields in instrospection

graphql/introspection/type.go

@@ -1,6 +1,8 @@
 package introspection
 
 import (
+	"strings"
+
 	"github.com/vektah/gqlparser/ast"
 )
 
@@ -63,6 +65,10 @@ func (t *Type) Fields(includeDeprecated bool) []Field {
 	}
 	var fields []Field
 	for _, f := range t.def.Fields {
+		if strings.HasPrefix(f.Name, "__") {
+			continue
+		}
+
 		fields = append(fields, Field{
 			Name:              f.Name,
 			Description:       f.Description,

graphql/introspection/type_test.go

@@ -0,0 +1,36 @@
+package introspection
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/vektah/gqlparser/ast"
+)
+
+func TestType(t *testing.T) {
+	schemaType := Type{
+		def: &ast.Definition{
+			Name:        "Query",
+			Description: "test description",
+			Fields: ast.FieldList{
+				&ast.FieldDefinition{Name: "__schema"},
+				&ast.FieldDefinition{Name: "test"},
+			},
+			Kind: ast.Object,
+		},
+	}
+
+	t.Run("name", func(t *testing.T) {
+		require.Equal(t, "Query", schemaType.Name())
+	})
+
+	t.Run("description", func(t *testing.T) {
+		require.Equal(t, "test description", schemaType.Description())
+	})
+
+	t.Run("fields ", func(t *testing.T) {
+		fields := schemaType.Fields(false)
+		require.Len(t, fields, 1)
+		require.Equal(t, "test", fields[0].Name)
+	})
+}