def test_error_invalid_callable(self):
"""Test that an error is raised if the transform
is applied to an invalid function"""
with pytest.raises(
ValueError,
match="does not appear to be a valid Python function"):
qml.batch_transform(5)
def test_expand_qnode_with_kwarg(self, mocker, perform_expansion):
"""Test that kwargs are respected in the expansion."""
class MyTransform:
"""Dummy class to allow spying to work"""
def my_transform(self, tape, **kwargs):
tape1 = tape.copy()
tape2 = tape.copy()
return [tape1, tape2], None
spy_transform = mocker.spy(MyTransform, "my_transform")
transform_fn = qml.batch_transform(
MyTransform().my_transform, expand_fn=self.expand_logic_with_kwarg)
spy_expand = mocker.spy(transform_fn, "expand_fn")
dev = qml.device("default.qubit", wires=2)
@functools.partial(transform_fn, perform_expansion=perform_expansion)
@qml.qnode(dev)
def qnode(x):
qml.PhaseShift(0.5, wires=0)
return qml.expval(qml.PauliX(0))
qnode(0.2)
spy_transform.assert_called()
spy_expand.assert_called(
) # The expand_fn of transform_fn always is called
input_tape = spy_transform.call_args[0][1]
assert len(input_tape.operations) == 1
assert input_tape.operations[0].name == ("RZ" if perform_expansion else
"PhaseShift")
assert input_tape.operations[0].parameters == [0.5]
def test_expand_fn(self, mocker):
"""Test that if an expansion function is provided,
that the input tape is expanded before being transformed."""
class MyTransform:
"""Dummy class to allow spying to work"""
def my_transform(self, tape):
tape1 = tape.copy()
tape2 = tape.copy()
return [tape1, tape2], None
spy_transform = mocker.spy(MyTransform, "my_transform")
transform_fn = qml.batch_transform(MyTransform().my_transform,
expand_fn=self.phaseshift_expand)
with qml.tape.QuantumTape() as tape:
qml.PhaseShift(0.5, wires=0)
qml.expval(qml.PauliX(0))
spy_expand = mocker.spy(transform_fn, "expand_fn")
transform_fn(tape)
spy_transform.assert_called()
spy_expand.assert_called()
input_tape = spy_transform.call_args[0][1]
assert len(input_tape.operations) == 1
assert input_tape.operations[0].name == "RZ"
assert input_tape.operations[0].parameters == [0.5]
def test_expand_fn_with_kwarg(self, mocker, perform_expansion):
"""Test that kwargs are respected in the expansion."""
class MyTransform:
"""Dummy class to allow spying to work"""
def my_transform(self, tape, **kwargs):
tape1 = tape.copy()
tape2 = tape.copy()
return [tape1, tape2], None
spy_transform = mocker.spy(MyTransform, "my_transform")
transform_fn = qml.batch_transform(
MyTransform().my_transform, expand_fn=self.expand_logic_with_kwarg)
with qml.tape.QuantumTape() as tape:
qml.PhaseShift(0.5, wires=0)
qml.expval(qml.PauliX(0))
spy_expand = mocker.spy(transform_fn, "expand_fn")
transform_fn(tape, perform_expansion=perform_expansion)
spy_transform.assert_called()
spy_expand.assert_called(
) # The expand_fn of transform_fn always is called
input_tape = spy_transform.call_args[0][1]
assert len(input_tape.operations) == 1
assert input_tape.operations[0].name == ("RZ" if perform_expansion else
"PhaseShift")
assert input_tape.operations[0].parameters == [0.5]
def test_not_differentiable(self):
"""Test that a non-differentiable transform cannot be differentiated"""
def my_transform(tape):
tape1 = tape.copy()
tape2 = tape.copy()
return [tape1, tape2], qml.math.sum
my_transform = qml.batch_transform(my_transform, differentiable=False)
dev = qml.device("default.qubit", wires=2)
@my_transform
@qml.qnode(dev)
def circuit(x):
qml.Hadamard(wires=0)
qml.RY(x, wires=0)
return qml.expval(qml.PauliX(0))
res = circuit(0.5)
assert isinstance(res, float)
assert not np.allclose(res, 0)
with pytest.warns(UserWarning,
match="Output seems independent of input"):
qml.grad(circuit)(0.5)