public void When_generate_classes_is_called_then_nullable_enum_should_be_generated_correctly()
        {
            // Arrange
            var expected        = "export interface EnumModel\r\n{\r\n    status: ProductStatus | null;\r\n}\r\n\r\n";
            var systemUnderTest = new TypeScript()
                                  .AddType <EnumModel>();

            // Act
            string result = systemUnderTest.GenerateInterfaces();

            // Assert
            Assert.AreEqual(expected, result);
        }