WatiN + MbUnit
Verifying invalid input...
[RowTest]
[Row(null)]
[Row("")]
[Row("-12314132")]
[Row("foobar")]
[Row("very_long_string_very_long_string_and_so_on_for_another_512_chars")]
public void TryingToEnterWithInvlidPolicyNumberShowsError(string id)
{
Open("PolicyRequests/NewRequest.aspx?Id="+id);
AssertNoError();
AssertContainsText("Can't find Policy with id #"+id,"Should give error message for invalid input");
}