!7

sS testCases = [[
  if i make a list of 3 elements and add one more
    - how long is the new list?
  => 4 elements
  
  if i have a list of 10 elements - how long is it?
  => 10 elements
  
]];

p {
  L<S> lines = lines(testCases);
  L<Int> l = indexesOfLinesBeginningWithDoubleArrow(lines);
  int i = 0, cases = 0;
  for (int line : l) {
    S question = lines(subList(lines, i, line));
    S answer = trimDropPrefixTrim("=>", lines.get(line));
    i = line+1;
    
    assertContainsCodeTokensIC(answer, callAnswerFunctionVerbose(question));
    ++cases;
  }
  
  print("OK (" + n2(cases, 'case) + ")");
}

answer {
  new L<S> parts;
  L<S> l = tok_splitAtSpacedDashes(s);
  parts.addAll(tok_splitAtAndFromMiddle(l.get(0)));
  parts.add(l.get(1));
  pnl(parts);
  S answer = null;
  new Executor e;
  for (S part : parts) {
    print(part);
    e.process(part);
    L<S> out = cloneAndClearList(e.output);
    printLinesWithIndent(" => ", out);
    if (nempty(out)) answer = last(out);
  }
  try answer answer;
}

sclass Executor {
  int length = -1; // unknown
  new L<S> output;
  
  void say(S s) { output.add(s); }
    
  void process(S s) {
    L<S> tok = javaTok(s);

    int i = findCodeTokensIC(tok, "<int>", "elements");
    if (i >= 0) ret with length = parseInt(tok.get(i));

    if (hasCodeTokensIC(tok, "add", "one")) ret with ++length;
    
    if (hasCodeTokensIC(tok, "how", "long"))
      say("The list is " + n2(length, "element") + " long");
  }
}