old_contents: """Test bijection class."""
  import pytest
  
  from collections_extended.bijection import bijection
  
  
  def test_bijection():
  	"""General tests for bijection."""
  	b = bijection()
  	assert len(b) == 0
  	b['a'] = 1
  	assert len(b) == 1
  	assert b['a'] == 1
  	assert b.inverse[1] == 'a'
  	assert 'a' in b
  	assert 1 not in b
  	assert 1 in b.inverse
  	with pytest.raises(KeyError):
  		del b['f']
  	assert b == bijection(a=1)
  	assert b.inverse.inverse is b
  	assert b == b.copy()
  	del b['a']
  	assert b == bijection()
  	assert bijection(a=1, b=2, c=3) == bijection({'a': 1, 'b': 2, 'c': 3})
  	b['a'] = 1
  	b.inverse[1] = 'b'
  	assert 'b' in b
  	assert b['b'] == 1
  	assert 'a' not in b
  
new_contents: """Test bijection class."""
  import pytest
  
  from collections_extended.bijection import bijection
  
  
  def test_bijection():
  	"""General tests for bijection."""
  	b = bijection()
  	assert len(b) == 0
  	b['a'] = 1
  	assert len(b) == 1
  	assert b['a'] == 1
  	assert b.inverse[1] == 'a'
  	assert 'a' in b
  	assert 1 not in b
  	assert 1 in b.inverse
  	with pytest.raises(KeyError):
  		del b['f']
  	assert b == bijection(a=1)
  	assert b.inverse.inverse is b
  	assert b == b.copy()
  	del b['a']
  	assert b == bijection()
  	assert bijection(a=1, b=2, c=3) == bijection({'a': 1, 'b': 2, 'c': 3})
  	b['a'] = 1
  	b.inverse[1] = 'b'
  	assert 'b' in b
  	assert b['b'] == 1
  	assert 'a' not in b
  
  
  def test_init_from_pairs():
  	assert bijection({'a': 1, 'b': 2}) == bijection((('a', 1), ('b', 2)))
  
subject: Add test for bijection init from list of pairs