Improve test suite speed: pytest-xdist; qcut and qchem markers; update reconstruct tests

.github/workflows/tests.yml

@@ -45,11 +45,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install -r requirements-ci.txt
-          pip install wheel pytest pytest-cov pytest-mock flaky --upgrade
-
-      - name: Conditionally install openfermionpyscf
-        if: contains(' 3.9', matrix.config.python-version)
-        run: pip3 install openfermionpyscf
+          pip install wheel pytest pytest-cov pytest-mock pytest-xdist flaky --upgrade
 
       - name: Conditionally install PyTorch
         if: contains(matrix.config.interfaces, 'torch')
@@ -65,9 +61,6 @@ jobs:
         if: contains(matrix.config.interfaces, 'jax')
         run: pip3 install jax jaxlib
 
-      - name: Install KaHyPar
-        run: pip3 install kahypar==1.1.7
-
       - name: Install PennyLane
         run: |
           pip install -r requirements-ci.txt
@@ -78,7 +71,7 @@ jobs:
         run: python -m pip install -i https://test.pypi.org/simple/ PennyLane-Lightning --pre --upgrade
 
       - name: Run tests
-        run: python -m pytest tests --cov=pennylane $COVERAGE_FLAGS
+        run: python -m pytest tests --cov=pennylane $COVERAGE_FLAGS -m "not qcut and not qchem" -n auto
 
       - name: Adjust coverage file for Codecov
         run: bash <(sed -i 's/filename=\"/filename=\"pennylane\//g' coverage.xml)
@@ -88,6 +81,100 @@ jobs:
         with:
           file: ./coverage.xml
 
+  qcut:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@0.4.1
+        with:
+          access_token: ${{ github.token }}
+
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 2
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.8
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements-ci.txt
+          pip install wheel pytest pytest-cov pytest-mock pytest-xdist flaky --upgrade
+
+      - name: Conditionally install TensorFlow
+        run: pip3 install tensorflow==$TF_VERSION keras==$TF_VERSION
+
+      - name: Install KaHyPar
+        run: pip3 install kahypar==1.1.7
+
+      - name: Install PennyLane
+        run: |
+          pip install -r requirements-ci.txt
+          python setup.py bdist_wheel
+          pip install dist/PennyLane*.whl
+
+      - name: Run tests
+        run: |
+          python -m pytest tests --cov=pennylane $COVERAGE_FLAGS -m qcut -n auto
+
+      - name: Adjust coverage file for Codecov
+        run: bash <(sed -i 's/filename=\"/filename=\"pennylane\//g' coverage.xml)
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v3
+        with:
+          file: ./coverage.xml
+
+  qchem:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@0.4.1
+        with:
+          access_token: ${{ github.token }}
+
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 2
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          # Based on previous experience, PySCF installation might fail or take
+          # longer time with some python versions
+          python-version: 3.9
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements-ci.txt
+          pip install wheel pytest pytest-cov pytest-mock pytest-xdist flaky --upgrade
+
+      - name: Install openfermionpyscf
+        run: pip3 install openfermionpyscf
+
+      - name: Install PennyLane
+        run: |
+          pip install -r requirements-ci.txt
+          python setup.py bdist_wheel
+          pip install dist/PennyLane*.whl
+
+      - name: Run tests
+        run: |
+          python -m pytest tests --cov=pennylane $COVERAGE_FLAGS -m qchem -n auto
+
+      - name: Adjust coverage file for Codecov
+        run: bash <(sed -i 's/filename=\"/filename=\"pennylane\//g' coverage.xml)
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v3
+        with:
+          file: ./coverage.xml
 
   device-tests:
     runs-on: ubuntu-latest
@@ -153,4 +240,4 @@ jobs:
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v3
         with:
-          file: ./coverage.xml
+          file: ./coverage.xml

tests/conftest.py

@@ -15,14 +15,14 @@
 Pytest configuration file for PennyLane test suite.
 """
 import os
+import pathlib
 
-import pytest
 import numpy as np
+import pytest
 
 import pennylane as qml
 from pennylane.devices import DefaultGaussian
 
-
 # defaults
 TOL = 1e-3
 TF_TOL = 2e-2
@@ -203,3 +203,13 @@ def mock_device(monkeypatch):
 def tear_down_hermitian():
     yield None
     qml.Hermitian._eigs = {}
+
+
+def pytest_collection_modifyitems(config, items):
+    # python 3.4/3.5 compat: rootdir = pathlib.Path(str(config.rootdir))
+    rootdir = pathlib.Path(config.rootdir)
+    for item in items:
+        rel_path = pathlib.Path(item.fspath).relative_to(rootdir)
+        if "qchem" in rel_path.parts:
+            mark = getattr(pytest.mark, "qchem")
+            item.add_marker(mark)

tests/devices/test_default_gaussian.py

@@ -712,7 +712,9 @@ def test_sample_error_multi_wire(self, gaussian_device_2_wires):
         with pytest.raises(ValueError, match="Only one mode can be measured in homodyne"):
             sample = gaussian_device_2_wires.sample("P", [0, 1], [])
 
-    @pytest.mark.parametrize("observable", set(qml.ops.cv.obs) - set(["P", "X", "QuadOperator"]))
+    @pytest.mark.parametrize(
+        "observable", sorted(set(qml.ops.cv.obs) - set(["P", "X", "QuadOperator"]))
+    )
     def test_sample_error_unsupported_observable(self, gaussian_device_2_wires, observable):
         """Test that the sample function raises an error if the given observable is not supported"""
 

tests/fourier/test_reconstruct.py

@@ -59,7 +59,7 @@ def circuit(x):
     return circuit
 
 
-def fun_close(fun1, fun2, zero=None, tol=1e-5, samples=100):
+def fun_close(fun1, fun2, zero=None, tol=1e-5, samples=10):
     X = np.linspace(-np.pi, np.pi, samples)
     if zero is not None:
         X = qml.math.convert_like(X, zero)
@@ -730,7 +730,7 @@ def qnode_2(X, y):
 
 
 def qnode_3(X, Y):
-    for i in range(5):
+    for i in range(3):
         qml.RX(X[i], wires=0)
         qml.RY(Y[i], wires=0)
         qml.RX(X[i], wires=0)
@@ -941,7 +941,7 @@ def test_differentiability_jax(
                 grad = jax.grad(rec)
                 assert np.isclose(grad(x0), exp_qnode_grad(*params)[inner_key])
                 assert np.isclose(grad(x0 + 0.1), exp_grad(x0 + 0.1))
-                assert fun_close(grad, exp_grad, 10)
+                assert fun_close(grad, exp_grad, samples=3)
 
     @pytest.mark.parametrize(
         "qnode, params, ids, nums_frequency, spectra, shifts, exp_calls",

tests/pytest.ini

@@ -2,5 +2,7 @@
 markers =
     slow: marks tests as slow (deselect with '-m "not slow"')
     gpu: marks tests run on a GPU (deselect with '-m "not gpu"')
+    qchem: marks tests for the QChem module (deselect with '-m "not qchem"')
+    qcut: marks tests for the QCut transform (deselect with '-m "not qcut"')
 filterwarnings = 
     ignore::DeprecationWarning:autograd.numpy.numpy_wrapper

tests/transforms/test_qcut.py

@@ -32,6 +32,8 @@
 from pennylane.transforms import qcut
 from pennylane.wires import Wires
 
+pytestmark = pytest.mark.qcut
+
 I, X, Y, Z = (
     np.eye(2),
     qml.PauliX.compute_matrix(),