public IToken AssertSingleToken()
{
Assert.True(2 == Tokens.Count, $"Expected token count {1}, was {Tokens.Count - 1} (excluding EOF)");
var eof = Tokens.Last().AssertOfType <IEndOfFileToken>();
Assert.Equal(new TextSpan(Tokens[Tokens.Count - 2].Span.End, 0), eof.Span);
return(Tokens[0]);
}
