Add tests for `znflow.Property`

[PythonFZ]

The following class is not tested enough.
Ideally, there would also be another way without entirely reimplementing the property class but I don't know how.

ZnFlow/znflow/base.py

Lines 23 to 73 in a24ee7c

	class Property:
	"""Custom Property with disabled graph.
	References
	----------
	Adapted from https://docs.python.org/3/howto/descriptor.html#properties
	"""
	def __init__(self, fget=None, fset=None, fdel=None, doc=None):
	self.fget = disable_graph()(fget)
	self.fset = disable_graph()(fset)
	self.fdel = disable_graph()(fdel)
	if doc is None and fget is not None:
	doc = fget.__doc__
	self.__doc__ = doc
	self._name = ""
	def __set_name__(self, owner, name):
	self._name = name
	def __get__(self, obj, objtype=None):
	if obj is None:
	return self
	if self.fget is None:
	raise AttributeError(f"property '{self._name}' has no getter")
	return self.fget(obj)
	def __set__(self, obj, value):
	if self.fset is None:
	raise AttributeError(f"property '{self._name}' has no setter")
	self.fset(obj, value)
	def __delete__(self, obj):
	if self.fdel is None:
	raise AttributeError(f"property '{self._name}' has no deleter")
	self.fdel(obj)
	def getter(self, fget):
	prop = type(self)(fget, self.fset, self.fdel, self.__doc__)
	prop._name = self._name
	return prop
	def setter(self, fset):
	prop = type(self)(self.fget, fset, self.fdel, self.__doc__)
	prop._name = self._name
	return prop
	def deleter(self, fdel):
	prop = type(self)(self.fget, self.fset, fdel, self.__doc__)
	prop._name = self._name
	return prop