text: import unittest
  from weakref import WeakSet
  import string
  from collections import UserString as ustr
  import gc
  import contextlib
  
  
  class Foo:
      pass
  
  class RefCycle:
      def __init__(self):
          self.cycle = self
  
  
  class TestWeakSet(unittest.TestCase):
  
      def setUp(self):
          # need to keep references to them
          self.items = [ustr(c) for c in ('a', 'b', 'c')]
          self.items2 = [ustr(c) for c in ('x', 'y', 'z')]
          self.ab_items = [ustr(c) for c in 'ab']
          self.abcde_items = [ustr(c) for c in 'abcde']
          self.def_items = [ustr(c) for c in 'def']
          self.ab_weakset = WeakSet(self.ab_items)
          self.abcde_weakset = WeakSet(self.abcde_items)
          self.def_weakset = WeakSet(self.def_items)
          self.letters = [ustr(c) for c in string.ascii_letters]
          self.s = WeakSet(self.items)
          self.d = dict.fromkeys(self.items)
          self.obj = ustr('F')
          self.fs = WeakSet([self.obj])
  
      def test_methods(self):
          weaksetmethods = dir(WeakSet)
          for method in dir(set):
              if method == 'test_c_api' or method.startswith('_'):
                  continue
              self.assertIn(method, weaksetmethods,
                           "WeakSet missing method " + method)
  
      def test_new_or_init(self):
          self.assertRaises(TypeError, WeakSet, [], 2)
  
      def test_len(self):
          self.assertEqual(len(self.s), len(self.d))
          self.assertEqual(len(self.fs), 1)
          del self.obj
          self.assertEqual(len(self.fs), 0)
  
      def test_contains(self):
          for c in self.letters:
              self.assertEqual(c in self.s, c in self.d)
          # 1 is not weakref'able, but that TypeError is caught by __contains__
          self.assertNotIn(1, self.s)
          self.assertIn(self.obj, self.fs)
          del self.obj
          self.assertNotIn(ustr('F'), self.fs)
  
      def test_union(self):
          u = self.s.union(self.items2)
          for c in self.letters:
              self.assertEqual(c in u, c in self.d or c in self.items2)
          self.assertEqual(self.s, WeakSet(self.items))
          self.assertEqual(type(u), WeakSet)
          self.assertRaises(TypeError, self.s.union, [[]])
          for C in set, frozenset, dict.fromkeys, list, tuple:
              x = WeakSet(self.items + self.items2)
              c = C(self.items2)
              self.assertEqual(self.s.union(c), x)
              del c
          self.assertEqual(len(u), len(self.items) + len(self.items2))
          self.items2.pop()
          gc.collect()
          self.assertEqual(len(u), len(self.items) + len(self.items2))
  
      def test_or(self):
          i = self.s.union(self.items2)
          self.assertEqual(self.s | set(self.items2), i)
          self.assertEqual(self.s | frozenset(self.items2), i)
  
      def test_intersection(self):
          s = WeakSet(self.letters)
          i = s.intersection(self.items2)
          for c in self.letters:
              self.assertEqual(c in i, c in self.items2 and c in self.letters)
          self.assertEqual(s, WeakSet(self.letters))
          self.assertEqual(type(i), WeakSet)
          for C in set, frozenset, dict.fromkeys, list, tuple:
              x = WeakSet([])
              self.assertEqual(i.intersection(C(self.items)), x)
          self.assertEqual(len(i), len(self.items2))
          self.items2.pop()
          gc.collect()
          self.assertEqual(len(i), len(self.items2))
  
      def test_isdisjoint(self):
          self.assertTrue(self.s.isdisjoint(WeakSet(self.items2)))
          self.assertTrue(not self.s.isdisjoint(WeakSet(self.letters)))
  
      def test_and(self):
          i = self.s.intersection(self.items2)
          self.assertEqual(self.s & set(self.items2), i)
          self.assertEqual(self.s & frozenset(self.items2), i)
  
      def test_difference(self):
          i = self.s.difference(self.items2)
          for c in self.letters:
              self.assertEqual(c in i, c in self.d and c not in self.items2)
          self.assertEqual(self.s, WeakSet(self.items))
          self.assertEqual(type(i), WeakSet)
          self.assertRaises(TypeError, self.s.difference, [[]])
  
      def test_sub(self):
          i = self.s.difference(self.items2)
          self.assertEqual(self.s - set(self.items2), i)
          self.assertEqual(self.s - frozenset(self.items2), i)
  
      def test_symmetric_difference(self):
          i = self.s.symmetric_difference(self.items2)
          for c in self.letters:
              self.assertEqual(c in i, (c in self.d) ^ (c in self.items2))
          self.assertEqual(self.s, WeakSet(self.items))
          self.assertEqual(type(i), WeakSet)
          self.assertRaises(TypeError, self.s.symmetric_difference, [[]])
          self.assertEqual(len(i), len(self.items) + len(self.items2))
          self.items2.pop()
          gc.collect()
          self.assertEqual(len(i), len(self.items) + len(self.items2))
  
      def test_xor(self):
          i = self.s.symmetric_difference(self.items2)
          self.assertEqual(self.s ^ set(self.items2), i)
          self.assertEqual(self.s ^ frozenset(self.items2), i)
  
      def test_sub_and_super(self):
          self.assertTrue(self.ab_weakset <= self.abcde_weakset)
          self.assertTrue(self.abcde_weakset <= self.abcde_weakset)
          self.assertTrue(self.abcde_weakset >= self.ab_weakset)
          self.assertFalse(self.abcde_weakset <= self.def_weakset)
          self.assertFalse(self.abcde_weakset >= self.def_weakset)
          self.assertTrue(set('a').issubset('abc'))
          self.assertTrue(set('abc').issuperset('a'))
          self.assertFalse(set('a').issubset('cbs'))
          self.assertFalse(set('cbs').issuperset('a'))
  
      def test_lt(self):
          self.assertTrue(self.ab_weakset < self.abcde_weakset)
          self.assertFalse(self.abcde_weakset < self.def_weakset)
          self.assertFalse(self.ab_weakset < self.ab_weakset)
          self.assertFalse(WeakSet() < WeakSet())
  
      def test_gt(self):
          self.assertTrue(self.abcde_weakset > self.ab_weakset)
          self.assertFalse(self.abcde_weakset > self.def_weakset)
          self.assertFalse(self.ab_weakset > self.ab_weakset)
          self.assertFalse(WeakSet() > WeakSet())
  
      def test_gc(self):
          # Create a nest of cycles to exercise overall ref count check
          s = WeakSet(Foo() for i in range(1000))
          for elem in s:
              elem.cycle = s
              elem.sub = elem
              elem.set = WeakSet([elem])
  
      def test_subclass_with_custom_hash(self):
          # Bug #1257731
          class H(WeakSet):
              def __hash__(self):
                  return int(id(self) & 0x7fffffff)
          s=H()
          f=set()
          f.add(s)
          self.assertIn(s, f)
          f.remove(s)
          f.add(s)
          f.discard(s)
  
      def test_init(self):
          s = WeakSet()
          s.__init__(self.items)
          self.assertEqual(s, self.s)
          s.__init__(self.items2)
          self.assertEqual(s, WeakSet(self.items2))
          self.assertRaises(TypeError, s.__init__, s, 2);
          self.assertRaises(TypeError, s.__init__, 1);
  
      def test_constructor_identity(self):
          s = WeakSet(self.items)
          t = WeakSet(s)
          self.assertNotEqual(id(s), id(t))
  
      def test_hash(self):
          self.assertRaises(TypeError, hash, self.s)
  
      def test_clear(self):
          self.s.clear()
          self.assertEqual(self.s, WeakSet([]))
          self.assertEqual(len(self.s), 0)
  
      def test_copy(self):
          dup = self.s.copy()
          self.assertEqual(self.s, dup)
          self.assertNotEqual(id(self.s), id(dup))
  
      def test_add(self):
          x = ustr('Q')
          self.s.add(x)
          self.assertIn(x, self.s)
          dup = self.s.copy()
          self.s.add(x)
          self.assertEqual(self.s, dup)
          self.assertRaises(TypeError, self.s.add, [])
          self.fs.add(Foo())
          self.assertTrue(len(self.fs) == 1)
          self.fs.add(self.obj)
          self.assertTrue(len(self.fs) == 1)
  
      def test_remove(self):
          x = ustr('a')
          self.s.remove(x)
          self.assertNotIn(x, self.s)
          self.assertRaises(KeyError, self.s.remove, x)
          self.assertRaises(TypeError, self.s.remove, [])
  
      def test_discard(self):
          a, q = ustr('a'), ustr('Q')
          self.s.discard(a)
          self.assertNotIn(a, self.s)
          self.s.discard(q)
          self.assertRaises(TypeError, self.s.discard, [])
  
      def test_pop(self):
          for i in range(len(self.s)):
              elem = self.s.pop()
              self.assertNotIn(elem, self.s)
          self.assertRaises(KeyError, self.s.pop)
  
      def test_update(self):
          retval = self.s.update(self.items2)
          self.assertEqual(retval, None)
          for c in (self.items + self.items2):
              self.assertIn(c, self.s)
          self.assertRaises(TypeError, self.s.update, [[]])
  
      def test_update_set(self):
          self.s.update(set(self.items2))
          for c in (self.items + self.items2):
              self.assertIn(c, self.s)
  
      def test_ior(self):
          self.s |= set(self.items2)
          for c in (self.items + self.items2):
              self.assertIn(c, self.s)
  
      def test_intersection_update(self):
          retval = self.s.intersection_update(self.items2)
          self.assertEqual(retval, None)
          for c in (self.items + self.items2):
              if c in self.items2 and c in self.items:
                  self.assertIn(c, self.s)
              else:
                  self.assertNotIn(c, self.s)
          self.assertRaises(TypeError, self.s.intersection_update, [[]])
  
      def test_iand(self):
          self.s &= set(self.items2)
          for c in (self.items + self.items2):
              if c in self.items2 and c in self.items:
                  self.assertIn(c, self.s)
              else:
                  self.assertNotIn(c, self.s)
  
      def test_difference_update(self):
          retval = self.s.difference_update(self.items2)
          self.assertEqual(retval, None)
          for c in (self.items + self.items2):
              if c in self.items and c not in self.items2:
                  self.assertIn(c, self.s)
              else:
                  self.assertNotIn(c, self.s)
          self.assertRaises(TypeError, self.s.difference_update, [[]])
          self.assertRaises(TypeError, self.s.symmetric_difference_update, [[]])
  
      def test_isub(self):
          self.s -= set(self.items2)
          for c in (self.items + self.items2):
              if c in self.items and c not in self.items2:
                  self.assertIn(c, self.s)
              else:
                  self.assertNotIn(c, self.s)
  
      def test_symmetric_difference_update(self):
          retval = self.s.symmetric_difference_update(self.items2)
          self.assertEqual(retval, None)
          for c in (self.items + self.items2):
              if (c in self.items) ^ (c in self.items2):
                  self.assertIn(c, self.s)
              else:
                  self.assertNotIn(c, self.s)
          self.assertRaises(TypeError, self.s.symmetric_difference_update, [[]])
  
      def test_ixor(self):
          self.s ^= set(self.items2)
          for c in (self.items + self.items2):
              if (c in self.items) ^ (c in self.items2):
                  self.assertIn(c, self.s)
              else:
                  self.assertNotIn(c, self.s)
  
      def test_inplace_on_self(self):
          t = self.s.copy()
          t |= t
          self.assertEqual(t, self.s)
          t &= t
          self.assertEqual(t, self.s)
          t -= t
          self.assertEqual(t, WeakSet())
          t = self.s.copy()
          t ^= t
          self.assertEqual(t, WeakSet())
  
      def test_eq(self):
          # issue 5964
          self.assertTrue(self.s == self.s)
          self.assertTrue(self.s == WeakSet(self.items))
          self.assertFalse(self.s == set(self.items))
          self.assertFalse(self.s == list(self.items))
          self.assertFalse(self.s == tuple(self.items))
          self.assertFalse(self.s == WeakSet([Foo]))
          self.assertFalse(self.s == 1)
  
      def test_ne(self):
          self.assertTrue(self.s != set(self.items))
          s1 = WeakSet()
          s2 = WeakSet()
          self.assertFalse(s1 != s2)
  
      def test_weak_destroy_while_iterating(self):
          # Issue #7105: iterators shouldn't crash when a key is implicitly removed
          # Create new items to be sure no-one else holds a reference
          items = [ustr(c) for c in ('a', 'b', 'c')]
          s = WeakSet(items)
          it = iter(s)
          next(it)             # Trigger internal iteration
          # Destroy an item
          del items[-1]
          gc.collect()    # just in case
          # We have removed either the first consumed items, or another one
          self.assertIn(len(list(it)), [len(items), len(items) - 1])
          del it
          # The removal has been committed
          self.assertEqual(len(s), len(items))
  
      def test_weak_destroy_and_mutate_while_iterating(self):
          # Issue #7105: iterators shouldn't crash when a key is implicitly removed
          items = [ustr(c) for c in string.ascii_letters]
          s = WeakSet(items)
          @contextlib.contextmanager
          def testcontext():
              try:
                  it = iter(s)
                  # Start iterator
                  yielded = ustr(str(next(it)))
                  # Schedule an item for removal and recreate it
                  u = ustr(str(items.pop()))
                  if yielded == u:
                      # The iterator still has a reference to the removed item,
                      # advance it (issue #20006).
                      next(it)
                  gc.collect()      # just in case
                  yield u
              finally:
                  it = None           # should commit all removals
  
          with testcontext() as u:
              self.assertNotIn(u, s)
          with testcontext() as u:
              self.assertRaises(KeyError, s.remove, u)
          self.assertNotIn(u, s)
          with testcontext() as u:
              s.add(u)
          self.assertIn(u, s)
          t = s.copy()
          with testcontext() as u:
              s.update(t)
          self.assertEqual(len(s), len(t))
          with testcontext() as u:
              s.clear()
          self.assertEqual(len(s), 0)
  
      def test_len_cycles(self):
          N = 20
          items = [RefCycle() for i in range(N)]
          s = WeakSet(items)
          del items
          it = iter(s)
          try:
              next(it)
          except StopIteration:
              pass
          gc.collect()
          n1 = len(s)
          del it
          gc.collect()
          n2 = len(s)
          # one item may be kept alive inside the iterator
          self.assertIn(n1, (0, 1))
          self.assertEqual(n2, 0)
  
      def test_len_race(self):
          # Extended sanity checks for len() in the face of cyclic collection
          self.addCleanup(gc.set_threshold, *gc.get_threshold())
          for th in range(1, 100):
              N = 20
              gc.collect(0)
              gc.set_threshold(th, th, th)
              items = [RefCycle() for i in range(N)]
              s = WeakSet(items)
              del items
              # All items will be collected at next garbage collection pass
              it = iter(s)
              try:
                  next(it)
              except StopIteration:
                  pass
              n1 = len(s)
              del it
              n2 = len(s)
              self.assertGreaterEqual(n1, 0)
              self.assertLessEqual(n1, N)
              self.assertGreaterEqual(n2, 0)
              self.assertLessEqual(n2, n1)
  
      def test_repr(self):
          assert repr(self.s) == repr(self.s.data)
  
  
  if __name__ == "__main__":
      unittest.main()
  