public void Then_correct_errors_are_returned(string input, string filetype, bool isValid) { var validator = new FileTypeValidator { ValidationDefinition = new ValidationDefinition() { ErrorMessage = "Incorrect FileType", Name = "FileType", Value = filetype } }; var question = new Question { QuestionId = "Q1" }; var errors = validator.Validate(question, new Answer { Value = input, QuestionId = question.QuestionId }); (errors.Count is 0).Should().Be(isValid); }