move legacy tests to its own directory

tests_legacy/.pylintrc

@@ -0,0 +1,52 @@
+[MASTER]
+# A comma-separated list of package or module names from where C extensions may
+# be loaded. Extensions are loading into the active Python interpreter and may
+# run arbitrary code
+extension-pkg-whitelist=numpy,scipy,autograd,toml,appdir,autograd.numpy,autograd.numpy.linalg,autograd.numpy.builtins,semantic_version,torch,tensorflow,tensorflow.contrib,tensorflow.contrib.eager,LazyLoader,networkx,networkx.dag
+ignore-patterns=test_legacy*
+
+[TYPECHECK]
+
+# List of module names for which member attributes should not be checked
+# (useful for modules/projects where namespaces are manipulated during runtime
+# and thus existing member attributes cannot be deduced by static analysis. It
+# supports qualified module names, as well as Unix pattern matching.
+ignored-modules=numpy,scipy,autograd,toml,appdir,autograd.numpy,autograd.numpy.linalg,autograd.numpy.builtins,semantic_version,torch,tensorflow,tensorflow.contrib,tensorflow.contrib.eager,LazyLoader,networkx,networkx.dag,math,pennylane.numpy
+
+# List of classes names for which member attributes should not be checked
+# (useful for classes with attributes dynamically set). This supports can work
+# with qualified names.
+ignored-classes=numpy,scipy,autograd,toml,appdir,autograd.numpy,autograd.numpy.linalg,autograd.numpy.builtins,semantic_version,torch,tensorflow,tensorflow.contrib,tensorflow.contrib.eager,LazyLoader,networkx,networkx.dag,math,pennylane.numpy,pennylane.numpy.random,pennylane.numpy.linalg,pennylane.numpy.builtins,pennylane.operation,rustworkx,kahypar
+
+[MESSAGES CONTROL]
+
+# Enable the message, report, category or checker with the given id(s). You can
+# either give multiple identifier separated by comma (,) or put this option
+# multiple time.
+#enable=
+
+# Disable the message, report, category or checker with the given id(s). You
+# can either give multiple identifier separated by comma (,) or put this option
+# multiple time (only on the command line, not in the configuration file where
+# it should appear only once).
+# Cyclical import checks are disabled for now as they are frequently used in
+# the code base, but this can be removed in the future once cycles are resolved.
+disable=
+  line-too-long,
+  invalid-name,
+  too-many-lines,
+  redefined-builtin,
+  too-many-locals,
+  duplicate-code,
+  cyclic-import,
+  import-error,
+  bad-option-value,
+  import-outside-toplevel,
+  missing-class-docstring,
+  missing-function-docstring,
+  no-self-use
+
+[MISCELLANEOUS]
+
+# List of note tags to take in consideration, separated by a comma.
+notes=

tests_legacy/conftest.py

@@ -0,0 +1,133 @@
+# Copyright 2018-2023 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.
+"""
+Pytest configuration file for PennyLane-Lightning test suite.
+"""
+import os
+
+import pytest
+import numpy as np
+
+import pennylane as qml
+
+# defaults
+TOL = 1e-6
+TOL_STOCHASTIC = 0.05
+
+U = np.array(
+    [
+        [0.83645892 - 0.40533293j, -0.20215326 + 0.30850569j],
+        [-0.23889780 - 0.28101519j, -0.88031770 - 0.29832709j],
+    ]
+)
+
+U2 = np.array(
+    [
+        [
+            -0.07843244 - 3.57825948e-01j,
+            0.71447295 - 5.38069384e-02j,
+            0.20949966 + 6.59100734e-05j,
+            -0.50297381 + 2.35731613e-01j,
+        ],
+        [
+            -0.26626692 + 4.53837083e-01j,
+            0.27771991 - 2.40717436e-01j,
+            0.41228017 - 1.30198687e-01j,
+            0.01384490 - 6.33200028e-01j,
+        ],
+        [
+            -0.69254712 - 2.56963068e-02j,
+            -0.15484858 + 6.57298384e-02j,
+            -0.53082141 + 7.18073414e-02j,
+            -0.41060450 - 1.89462315e-01j,
+        ],
+        [
+            -0.09686189 - 3.15085273e-01j,
+            -0.53241387 - 1.99491763e-01j,
+            0.56928622 + 3.97704398e-01j,
+            -0.28671074 - 6.01574497e-02j,
+        ],
+    ]
+)
+
+THETA = np.linspace(0.11, 1, 3)
+PHI = np.linspace(0.32, 1, 3)
+VARPHI = np.linspace(0.02, 1, 3)
+
+
+@pytest.fixture(scope="session")
+def tol():
+    """Numerical tolerance for equality tests."""
+    return float(os.environ.get("TOL", TOL))
+
+
+@pytest.fixture(scope="session")
+def tol_stochastic():
+    """Numerical tolerance for equality tests."""
+    return TOL_STOCHASTIC
+
+
+@pytest.fixture(scope="session", params=[2, 3])
+def n_subsystems(request):
+    """Number of qubits or qumodes."""
+    return request.param
+
+
+# Looking for the device for testing.
+default_device = "lightning.qubit"
+supported_devices = {"lightning.kokkos", "lightning.qubit"}
+supported_devices.update({sb.replace(".", "_") for sb in supported_devices})
+
+
+def get_device():
+    """Return the pennylane lightning device.
+
+    The device is ``lightning.qubit`` by default.
+    Allowed values are: "lightning.kokkos" and "lightning.qubit".
+    An underscore can also be used instead of a dot.
+    If the environment variable ``PL_DEVICE`` is defined, its value is used.
+    Underscores are replaced by dots upon exiting.
+    """
+    device = None
+    if "PL_DEVICE" in os.environ:
+        device = os.environ.get("PL_DEVICE", default_device)
+        device = device.replace("_", ".")
+    if device is None:
+        device = default_device
+    if device not in supported_devices:
+        raise ValueError(f"Invalid backend {device}.")
+    return device
+
+
+device_name = get_device()
+
+if device_name not in qml.plugin_devices:
+    raise qml.DeviceError(
+        f"Device {device_name} does not exist. Make sure the required plugin is installed."
+    )
+
+# Device specification
+if device_name == "lightning.kokkos":
+    from pennylane_lightning.lightning_kokkos import LightningKokkos as LightningDevice
+else:
+    from pennylane_lightning.lightning_qubit import LightningQubit as LightningDevice
+
+
+# General qubit_device fixture, for any number of wires.
+@pytest.fixture(scope="function", params=[np.complex64, np.complex128])
+def qubit_device(request):
+    def _device(wires):
+        return qml.device(device_name, wires=wires, c_dtype=request.param)
+
+    return _device

tests_legacy/lightning_qubit/test_measurements_samples_MCMC.py

@@ -0,0 +1,100 @@
+# Copyright 2018-2023 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.
+"""
+Unit tests for MCMC sampling in lightning.qubit.
+"""
+import pytest
+from conftest import LightningDevice  # tested device
+
+import numpy as np
+import pennylane as qml
+
+import pytest
+
+from pennylane_lightning.lightning_qubit import LightningQubit
+
+
+if not LightningQubit._CPP_BINARY_AVAILABLE:
+    pytest.skip("No binary module found. Skipping.", allow_module_level=True)
+
+if LightningDevice != LightningQubit:
+    pytest.skip("Exclusive tests for lightning.qubit. Skipping.", allow_module_level=True)
+
+
+class TestMCMCSample:
+    """Tests that samples are properly calculated."""
+
+    @pytest.fixture(params=[np.complex64, np.complex128])
+    def dev(self, request):
+        return qml.device("lightning.qubit", wires=2, shots=1000, mcmc=True, c_dtype=request.param)
+
+    test_data_no_parameters = [
+        (100, [0], qml.PauliZ(wires=[0]), 100),
+        (110, [1], qml.PauliZ(wires=[1]), 110),
+        (120, [0, 1], qml.PauliX(0) @ qml.PauliZ(1), 120),
+    ]
+
+    @pytest.mark.parametrize("num_shots,measured_wires,operation,shape", test_data_no_parameters)
+    def test_mcmc_sample_dimensions(self, dev, num_shots, measured_wires, operation, shape):
+        """Tests if the samples returned by sample have
+        the correct dimensions
+        """
+        dev.apply([qml.RX(1.5708, wires=[0]), qml.RX(1.5708, wires=[1])])
+
+        dev.shots = num_shots
+        dev._wires_measured = measured_wires
+        dev._samples = dev.generate_samples()
+        s1 = dev.sample(operation)
+
+        assert np.array_equal(s1.shape, (shape,))
+
+    @pytest.mark.parametrize("kernel", ["Local", "NonZeroRandom"])
+    def test_sample_values(self, tol, kernel):
+        """Tests if the samples returned by sample have
+        the correct values
+        """
+        dev = qml.device(
+            "lightning.qubit", wires=2, shots=1000, mcmc=True, kernel_name=kernel, num_burnin=100
+        )
+
+        dev.apply([qml.RX(1.5708, wires=[0])])
+        dev._wires_measured = {0}
+        dev._samples = dev.generate_samples()
+        s1 = dev.sample(qml.PauliZ(0))
+
+        # s1 should only contain 1 and -1, which is guaranteed if
+        # they square to 1
+        assert np.allclose(s1**2, 1, atol=tol, rtol=0)
+
+    @pytest.mark.parametrize("kernel", ["local", "nonZeroRandom", "Global", "global"])
+    def test_unsupported_sample_kernels(self, tol, kernel):
+        """Tests if the samples returned by sample have
+        the correct values
+        """
+        with pytest.raises(
+            NotImplementedError,
+            match=f"The {kernel} is not supported and currently only 'Local' and 'NonZeroRandom' kernels are supported.",
+        ):
+            dev = qml.device(
+                "lightning.qubit",
+                wires=2,
+                shots=1000,
+                mcmc=True,
+                kernel_name=kernel,
+                num_burnin=100,
+            )
+
+    def test_wrong_num_burnin(self):
+        with pytest.raises(ValueError, match="Shots should be greater than num_burnin."):
+            dev = qml.device("lightning.qubit", wires=2, shots=1000, mcmc=True, num_burnin=1000)