def test_extract_qubits():
p = Program(RX(0.5)(0), RY(0.1)(1), RZ(1.4)(2))
assert p.extract_qubits() == set([0, 1, 2])
p.if_then(0, X(4), H(5)).measure(6, 2)
assert p.extract_qubits() == set([0, 1, 2, 4, 5, 6])
p.while_do(0, Program(X(3)).measure(3, 0))
assert p.extract_qubits() == set([0, 1, 2, 3, 4, 5, 6])
new_qubit = p.alloc()
p.inst(X(new_qubit))
p.synthesize()
assert p.extract_qubits() == set([0, 1, 2, 3, 4, 5, 6, new_qubit.index()])
