private string GetRandomString(char start, int alphabetSize, int length)
{
Debug.Assert(alphabetSize <= 26);
char[] s = new char[2 * length];
for (int charIDX = 0; charIDX < length; charIDX++)
{
s[2 * charIDX] = (char)(start + Random().Next(alphabetSize));
s[2 * charIDX + 1] = ' ';
}
return new string(s);
}