public int size() {
    return map.size();
  }
@Test
  public void testSize() {
    assertEquals(0, map.size());

    // put a key
    map.put("foo", () -> "foovalue");
    assertEquals(1, map.size());

    // put a different key
    map.put("bar", () -> "foovalue2");
    assertEquals(2, map.size());

    // put the same key again
    map.put("bar", () -> "foovalue3");
    assertEquals(2, map.size()); // map should be same size
  }