from catopt_query.canonical import CanonicalPlan
from catopt_query.solver import optimize_across_shards
from catopt_query.protocol import PlanDelta


def test_solver_composes_plans():
    p1 = CanonicalPlan(projection=["a"], predicates=["a>0"], estimated_cost=1.0)
    p2 = CanonicalPlan(projection=["b"], predicates=["b<5"], estimated_cost=2.0)
    delta = optimize_across_shards([p1, p2], bandwidth_budget=10.0)
    assert isinstance(delta, PlanDelta)
    assert "projections" in delta.changes
    assert "aggregated_cost" in delta.changes