def test_V():
"""Test for the _make_V function"""
dim = 4
V_expected = -np.eye(dim)
V_expected[1, 1] = V_expected[3, 3] = 1
V = _make_V(dim)
assert np.allclose(V, V_expected)
def test_apply_controlled_v(n_wires):
"""Test if the _apply_controlled_v performs the correct transformation by reconstructing the
unitary and comparing against the one provided in _make_V."""
n_all_wires = n_wires + 1
wires = Wires(range(n_wires))
control_wire = Wires(n_wires)
circ = lambda: _apply_controlled_v(target_wire=Wires([n_wires - 1]),
control_wire=control_wire)
u = get_unitary(circ, n_all_wires)
# Note the sign flip in the following. The sign does not matter when performing the Q unitary
# because two Vs are used.
v_ideal = -_make_V(2**n_wires)
circ = lambda: qml.ControlledQubitUnitary(
v_ideal, wires=wires, control_wires=control_wire)
u_ideal = get_unitary(circ, n_all_wires)
assert np.allclose(u, u_ideal)
