def test_instance_stack_is_not_the_same_as_class_level():
 class MyFs(io.FileSystem, ):
  pass
 MyFs.stack.append('foo')
 MyFs.stack.append('bar')
 assert_equals(MyFs().stack, [])

def test_instance_stack_is_not_the_same_as_class_level ( ) : class MyFs ( io . FileSystem , ) : pass MyFs . stack . append ( 'foo' ) MyFs . stack . append ( 'bar' ) assert_equals ( MyFs ( ) . stack , [ ] )
filesystem stack list has different lifecycle in filesystem objects .