// pass an empty instance

sclass ListTester {

  LS l;

  *(LS *l) {}

  *(LS *l, IF1<LS> *rotate) {}

  // parameters

  int n = 1000;

  int idLength = 5;

  // optional rotation to/from storagew

  int rotateAtLeastEvery = 20;

  swappable LS rotate(LS l) { ret l; }

  // output

  int rotationsDone;

  // internal

  int rotCountdown;

  Random random = predictableRandom();

  // Simple test

  run {

    assertEqualsVerbose(0, l.size());

    for (int i = -1; i < 2; i++) { int _i = i ; assertException(r { l.get(_i) }); }

    l.add("hello");

    rot();

    assertEqualsVerbose(1, l.size());

    assertException(r { l.get(-1) });

    assertEqualsVerbose("hello", l.get(0));

    assertException(r { l.get(1) });

    // n random insertions, complete check

    new LS refl;

    l.clear();

    repeat n {

      int i = random(random, l(refl)+1);

      S id = randomID(random, idLength);

      print("add " + i + " " + id);

      refl.add(i, id);

      l.add(i, id);

      rot();

      assertEquals(l(l), l(refl));

    }

    assertEqualsVerbose(l(l), l(refl));

    for i over refl:

      assertEquals(l.get(i), refl.get(i));

    // overwriting

    repeat n {

      int i = random(random, l(refl));

      S id = randomID(random);

      print("set " + i + " " + id);

      assertEquals(l.set(i, id), refl.set(i, id));

      assertEquals(l(l), l(refl));

      rot();

    }

    // n random deletions, check after each turn

    repeat n {

      int i = random(random, l(refl));

      print("remove " + i);

      assertEquals(l.remove(i), refl.remove(i));

      assertEqualsVerbose(l(l), l(refl));

      rot();

      for j over refl:

        assertEquals(l.get(j), refl.get(j));

    }

    test2();

  }

  void test2 {

    assertIndexOfAndContainsVerbose(l, "a", -1);

    l.add("a");

    rot();

    assertIndexOfAndContainsVerbose(l, "a", 0);

    assertIndexOfAndContainsVerbose(l, "b", -1);

    l.add("b");

    rot();

    assertIndexOfAndContainsVerbose(l, "a", 0);

    assertIndexOfAndContainsVerbose(l, "b", 1);

    l.add("a");

    rot();

    assertIndexOfAndContainsVerbose(l, "a", 0);

    l.remove(2);

    rot();

    assertIndexOfAndContainsVerbose(l, "a", 0);

    l.remove("a");

    rot();

    assertIndexOfAndContainsVerbose(l, "a", -1);

    assertIndexOfAndContainsVerbose(l, "b", 0);

    l.clear();

    rot();

    addAll(l, "a", "b", "c", "d");

    rot();

    l.subList(1, 3).clear();

    rot();

    assertEquals(ll("a", "d"), cloneList(l));

    LS sub = l.subList(1, 2);

    sub.set(0, "x");

    rot();

    assertEquals(1, sub.size()); // check modCount handling

    l.clear();

    rot();

    ok();

  }

  void ok {

    infoBox(className(l) + " works (tested up to size " + n + ")! :)");

  }

  void rot {

    if (rotCountdown <= 0)

      rotCountdown = random(random, rotateAtLeastEvery)+1;

    if (--rotCountdown <= 0) {

      l = rotate(l);

      rotationsDone++;

    }

  }

}