Event Sourcing - event code sample

event.py

class MyEvent:
    def __init__(self, foo: int):
        """For issuing new events in the application."""
        self.foo = foo

    @classmethod
    def unserialize(cls, payload: dict) -> "MyEvent":
        """To use when fetching an existing event from the event log."""
        return cls(foo=payload["foo"])

    def serialize(self) -> dict:
        """To use when storing a new event in the event log."""
        return {"foo": self.foo}


def test_my_event_serialize():
    event = MyEvent(1)

    assert event.serialize() == {"foo": 1}


def test_my_event_unserialize():
    assert MyEvent.unserialize({"foo": 1}) == MyEvent(1)