public void TestCharsFreqRemove()
{
string str = "qwqwertyuiopqwertyqwert";
Const c = new Const(str);
CharsFreqRemoveAdapter ad = new CharsFreqRemoveAdapter(c);
string tmp = ad.Calculate();
Assert.AreEqual(ad.Calculate(), "wwertywertywert");
}
// remove symbol
private void remove_symbol_Click(object sender, RoutedEventArgs e)
{
var f = new CharsFreqRemoveAdapter(new Const(remove_symb.Text));
f.Subformula = formula;
formula = f;
formula_text.Content = string.Format("{0} ! {1}",
formula_text.Content, remove_symb.Text);
remove_symb.Text = "";
}