- Memento - store originator object
- Originator - build/create mementos
- Caretaker - keep the memento
Every time we create new memento object, its state is taken from the originator element of the design pattern.
func TestNewMementoTakeOriginatorState(t *testing.T) {
firstState := originator{}
firstState.state = State{Description: "Idle"}
mem := firstState.NewMemento()
if mem.state.Description != "Idle" {
t.Error("Expected state was not found")
}
}
func (o *originator) NewMemento() memento {
return memento{state: o.state}
}In the following test state is changed to "working" to ensure that new state will be written.
func TestStoresIdleState(t *testing.T) {
originator := originator{state: State{"Idle"}}
idleMemento := originator.NewMemento()
originator.state.Description = "Working"
originator.ExtractAndStoreState(idleMemento)
if originator.state.Description != "Idle" {
t.Error("Unexpected state found")
}
}
func (o *originator) ExtractAndStoreState(m memento) {
o.state = m.state
}