HtmlInputRadioButtonTester.Checked Property

'True' if the radio button is checked; 'false' if not. Set this parameter to change the radio button value on post-back. Only one radio button in the same group (that is, with the same 'name' attribute) may be checked at any given time. If you set this radio button to true, any other radio buttons that are checked will be unchecked.

public bool Checked {get; set;}

See Also

HtmlInputRadioButtonTester Class | NUnit.Extensions.Asp.HtmlTester Namespace