from deltatrace.event_graph import EventGraph, Event, EventType


def test_event_graph_basic():
    g = EventGraph()
    e1 = Event.create(EventType.MD_TICK, {"symbol": "X"})
    e2 = Event.create(EventType.SIGNAL, {"strategy": "s1"})
    g.add_event(e1)
    g.add_event(e2)
    g.add_edge(e1.id, e2.id, label="t->s")

    roots = g.get_roots()
    assert any(r.id == e1.id for r in roots)
    children = g.get_children(e1.id)
    assert len(children) == 1 and children[0].id == e2.id