# Copyright 2018-2020 Xanadu Quantum Technologies Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Contains shared fixtures for the device tests."""
import os
import pytest
import numpy as np
import pennylane as qml
# ==========================================================
# pytest fixtures
# seed for random functions
np.random.seed(42)
# Tolerance for analytic tests
TOL = 1e-6
# Tolerance for non-analytic tests
TOL_STOCHASTIC = 0.05
# Number of shots to call the devices with
N_SHOTS = 10000
# List of all devices that are included in PennyLane
LIST_CORE_DEVICES = {"default.qubit", "default.qubit.tf"}
# TODO: add beta devices "default.tensor", "default.tensor.tf", which currently
# do not have an "analytic" attribute.
@pytest.fixture(scope="function")
def tol():
"""Numerical tolerance for equality tests. Returns a different tolerance for tests
probing analytic or non-analytic devices (yielding deterministic or stochastic test results)."""
def _tol(analytic):
if analytic:
return float(os.environ.get("TOL", TOL))
return TOL_STOCHASTIC
return _tol
@pytest.fixture(scope="session")
def init_state():
"""Fixture to create an n-qubit random initial state vector."""
def _init_state(n):
state = np.random.random([2 ** n]) + np.random.random([2 ** n]) * 1j
state /= np.linalg.norm(state)
return state
return _init_state
@pytest.fixture(scope="session")
def skip_if():
"""Fixture to skip tests."""
def _skip_if(dev, capabilities):
""" Skip test if device has any of the given capabilities. """
dev_capabilities = dev.capabilities()
for capability, value in capabilities.items():
# skip if capability not found, or if capability has specific value
if capability not in dev_capabilities or dev_capabilities[capability] == value:
pytest.skip(
"Test skipped for {} device with capability {}:{}.".format(
dev.name, capability, value
)
)
return _skip_if
@pytest.fixture(scope="function")
def device(device_kwargs):
"""Fixture to create a device."""
__tracebackhide__ = True
def _device(n_wires):
device_kwargs["wires"] = n_wires
try:
dev = qml.device(**device_kwargs)
except qml.DeviceError:
# exit the tests if the device cannot be created
pytest.exit(
"Device {} cannot be created. To run the device tests on an external device, the "
"plugin and all of its dependencies must be installed.".format(
device_kwargs["name"]
)
)
capabilities = dev.capabilities()
if "model" not in capabilities or not capabilities["model"] == "qubit":
# exit the tests if device based on cv model (currently not supported)
pytest.exit("The device test suite currently only runs on qubit-based devices.")
return dev
return _device
def pytest_runtest_setup(item):
"""Skip tests marked as broken."""
# skip tests marked as broken
for mark in item.iter_markers(name="broken"):
if mark.args:
pytest.skip("Broken test skipped: {}".format(*mark.args))
else:
pytest.skip("Test skipped as corresponding code base is currently broken!")
# ============================
# These functions are required to define the device name to run the tests for
def pytest_addoption(parser):
"""Add command line option to pytest."""
# The options are the three arguments every device takes
parser.addoption("--device", action="store", default=None)
parser.addoption("--shots", action="store", default=None, type=int)
parser.addoption("--analytic", action="store", default=None)
def pytest_generate_tests(metafunc):
"""Set up fixtures from command line options. """
opt = metafunc.config.option
device_kwargs = {
"name": opt.device,
"shots": opt.shots,
"analytic": opt.analytic,
}
# ===========================================
# some processing of the command line options
if device_kwargs["shots"] is None:
# use default value of device
device_kwargs.pop("shots")
if device_kwargs["analytic"] is None:
# use default value of device
device_kwargs.pop("analytic")
else:
if device_kwargs["analytic"].lower() == "false":
# turn string into boolean
device_kwargs["analytic"] = False
else:
device_kwargs["analytic"] = True
# ==============================================
# parametrize all functions that take device_kwargs as an argument
# this is needed for the "device" fixture
if "device_kwargs" in metafunc.fixturenames:
if opt.device is None:
# if no command line argument for device given, run tests on core devices
list_device_kwargs = []
for dev_name in LIST_CORE_DEVICES:
core_dev_kwargs = device_kwargs.copy()
core_dev_kwargs["name"] = dev_name
list_device_kwargs.append(core_dev_kwargs)
metafunc.parametrize("device_kwargs", list_device_kwargs)
else:
# run tests on specified device
metafunc.parametrize("device_kwargs", [device_kwargs])
