def test_global_state():
"""A Field can store its data in a global dict so that it can be recreated later with the same underlying data."""
ExecutionContext().install()
state_dict = {}
a = Field()
a.bind('x', a)
a.input_status = EmptyStub()
a.validation_error = EmptyStub()
a.user_input = EmptyStub()
a.parsed_input = EmptyStub()
a.activate_global_field_data_store(state_dict)
a.initial_value = EmptyStub()
b = Field()
b.bind('x', b)
assert a.initial_value is not b.initial_value
assert a.input_status is not b.input_status
assert a.validation_error is not b.validation_error
assert a.user_input is not b.user_input
assert a.parsed_input is not b.parsed_input
b.activate_global_field_data_store(state_dict)
assert a.initial_value is b.initial_value
assert a.input_status is b.input_status
assert a.validation_error is b.validation_error
assert a.user_input is b.user_input
assert a.parsed_input is b.parsed_input
def test_when_initial_value_is_read():
"""The initial_value of a Field is set upon first activate_global_field_data_store"""
ExecutionContext().install()
state_dict = {}
a = Field()
a.bind('x', a)
a.x = 'initial value for a'
assert not a.initial_value
a.activate_global_field_data_store(state_dict)
assert a.initial_value == a.x
a.x = 'changed value'
a.activate_global_field_data_store(state_dict)
assert a.initial_value != a.x
