def test_knapsack_problem_initial():
problem = KnapsackProblem(20, [(0, 0), (0, 0)])
assert problem.initial.capacity == 20
assert problem.value(problem.initial) == 0
assert problem.initial.weight == 0
def test_knapsack_value():
problem = KnapsackProblem(20, [(25, 30), (5, 9), (20, 200)])
state = KnapsackState(20, 20, 20, [False])
assert problem.value(state) == state.value