public void FormatExceptionTest()
        {
            var exception = new InvalidOperationException("some exception message");
            var actual    = exception.FormatException(x => x.AppendLine("A new line"));

            actual.Should()
            .Be("InvalidOperationException: some exception message\r\nA new line\r\n");
        }
        public void FormatExceptionNoActionTest()
        {
            var exception = new InvalidOperationException("some exception message");
            var actual    = exception.FormatException();

            actual.Should()
            .Be("InvalidOperationException: some exception message\r\n");
        }