@Test
public void nextWhenThereIsANext_returnsProperItem() {

  /* Given */
  SqlPart first = mock(SqlPart.class);
  SqlPart second = mock(SqlPart.class);
  when(first.previous()).thenReturn(second);
  SqlPartIterator iterator = new SqlPartIterator(first);
  iterator.next();
  /* When */
  SqlPart result = iterator.next();
  /* Then */
  assertThat(result, is(second));
}