text: import pytest
  
  from pex.orderedset import OrderedSet
  from pex.pex_info import PexInfo
  
  
  def make_pex_info(requirements):
    return PexInfo(info={'requirements': requirements})
  
  
  def test_backwards_incompatible_pex_info():
    # forwards compatibility
    pi = make_pex_info(['hello'])
    assert pi.requirements == OrderedSet(['hello'])
  
    pi = make_pex_info(['hello==0.1', 'world==0.2'])
    assert pi.requirements == OrderedSet(['hello==0.1', 'world==0.2'])
  
    # malformed
    with pytest.raises(ValueError):
      make_pex_info('hello')
  
    with pytest.raises(ValueError):
      make_pex_info([('hello', False)])
  
    # backwards compatibility
    pi = make_pex_info([
        ['hello==0.1', False, None],
        ['world==0.2', False, None],
    ])
    assert pi.requirements == OrderedSet(['hello==0.1', 'world==0.2'])
  