start linting test files

.github/tests/.pylintrc

@@ -0,0 +1,51 @@
+[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
+
+[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,retworkx,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=

.github/tests/tests_passing_pylint.txt

@@ -0,0 +1,2 @@
+tests/data/test_dataset.py
+tests/data/test_dataset_access.py

.github/tests/validate_new_tests.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+missing_files=()
+for file in $@
+do
+    if grep -Fxq $file .github/tests/tests_passing_pylint.txt
+    then
+        :
+    else
+        missing_files+=($file)
+    fi
+done
+
+if [ ${#missing_files[@]} -eq 0 ]; then
+    echo "All new test files are already added"
+    exit 0
+fi
+
+echo "Please add the following test files to ~/.github/tests/tests_passing_pylint.txt:"
+for file in ${missing_files[@]}; do echo $file; done
+exit 1

.github/workflows/pylint.yml

@@ -38,4 +38,38 @@ jobs:
           extra-flake8-options: ""
           extra-black-options: ""
           extra-mypy-options: ""
-          extra-isort-options: ""
+          extra-isort-options: ""
+
+      - name: Check for new test files that need whitelisting
+        uses: dorny/paths-filter@v2
+        id: test_files_added
+        with:
+          list-files: shell
+          filters: |
+            testsAdded:
+              - added: 'tests/**'
+
+      - name: Ensure new test files are whitelisted if there are any
+        if: steps.test_files_added.outputs.testsAdded == 'true'
+        run: ./.github/tests/validate_new_tests.sh ${{ steps.test_files_added.outputs.testsAdded_files }}
+
+      - name: Read whitelisted test files that pass pylint
+        id: tests_to_lint
+        run: echo "testfiles=$(cat .github/tests/tests_passing_pylint.txt | tr '\n' ' ')" >> $GITHUB_OUTPUT
+
+      - name: Run pylint for whitelisted tests
+        uses: ricardochaves/python-lint@v1.4.0
+        with:
+          python-root-list: "${{ steps.tests_to_lint.outputs.testfiles }}"
+          use-pylint: True
+          use-pycodestyle: false
+          use-flake8: false
+          use-black: false
+          use-mypy: false
+          use-isort: false
+          extra-pylint-options: "--rcfile .github/tests/.pylintrc"
+          extra-pycodestyle-options: ""
+          extra-flake8-options: ""
+          extra-black-options: ""
+          extra-mypy-options: ""
+          extra-isort-options: ""

Makefile

@@ -17,6 +17,8 @@ help:
 	@echo "  test               to run the test suite"
 	@echo "  coverage           to generate a coverage report"
 	@echo "  format [check=1]   to apply black formatter; use with 'check=1' to check instead of modify (requires black)"
+	@echo "  lint               to run pylint on source files"
+	@echo "  lint-test          to run pylint on test files"
 
 .PHONY: install
 install:
@@ -72,3 +74,11 @@ ifdef check
 else
 	black -l 100 ./pennylane ./tests
 endif
+
+.PHONY: lint
+lint:
+	pylint pennylane --rcfile .pylintrc
+
+.PHONY: lint-test
+lint-test:
+	pylint tests pennylane/devices/tests --rcfile .github/tests/.pylintrc

pennylane/collections/apply.py

@@ -16,6 +16,7 @@
 """
 
 
+# pylint:disable=unnecessary-lambda-assignment
 def apply(func, qnode_collection):
     """Apply a function to the constituent QNodes of a :class:`QNodeCollection`.
 

pennylane/collections/dot.py

@@ -14,7 +14,7 @@
 """
 Contains functions to implement the dot product between QNode collections
 """
-# pylint: disable=too-many-arguments,import-outside-toplevel
+# pylint: disable=too-many-arguments,import-outside-toplevel,unnecessary-lambda-assignment
 
 
 def _get_dot_func(interface, x=None):

pennylane/data/dataset.py

@@ -155,6 +155,7 @@ def attrs(self):
         """Returns attributes of the dataset."""
         return {k: v for k, v in vars(self).items() if k[0] != "_"}
 
+    # pylint:disable=c-extension-no-member
     @staticmethod
     def _read_file(filepath):
         """Read data from a saved file.
@@ -191,6 +192,7 @@ def read(self, filepath, lazy=False):
             data = None if lazy else self._read_file(filepath)
             setattr(self, f"{attribute}", data)
 
+    # pylint:disable=c-extension-no-member
     @staticmethod
     def _write_file(data, filepath, protocol=4):
         """General method to write data to a file."""

pennylane/devices/tests/test_gates.py

@@ -15,9 +15,7 @@
 Tests that application of gates and state preparations
 works correctly an a device.
 """
-# pylint: disable=no-self-use
-# pylint: disable=too-many-arguments
-# pylint: disable=pointless-statement
+# pylint:disable=no-self-use,too-many-arguments,pointless-statement,unnecessary-lambda-assignment
 from cmath import exp
 from math import cos, sin, sqrt
 

pennylane/devices/tests/test_properties.py

@@ -295,4 +295,4 @@ def circuit(x):
                 assert pnp.array(dev.access_state()).shape == orig_shape
 
         assert pnp.ndim(res) == 2
-        assert res.shape[0] == 3
+        assert res.shape[0] == 3  # pylint:disable=unsubscriptable-object

pennylane/math/is_independent.py

@@ -74,6 +74,7 @@ def _autograd_is_indep_analytic(func, *args, **kwargs):
     return True
 
 
+# pylint: disable=import-outside-toplevel,unnecessary-lambda-assignment,unnecessary-lambda
 def _jax_is_indep_analytic(func, *args, **kwargs):
     """Test analytically whether a function is independent of its arguments
     using JAX.
@@ -107,9 +108,9 @@ def _jax_is_indep_analytic(func, *args, **kwargs):
         This is an experimental function and unknown edge
         cases may exist to this two-stage test.
     """
-    import jax  # pylint: disable=import-outside-toplevel
+    import jax
 
-    mapped_func = lambda *_args: func(*_args, **kwargs)  # pylint: disable=unnecessary-lambda
+    mapped_func = lambda *_args: func(*_args, **kwargs)
     _vjp = jax.vjp(mapped_func, *args)[1]
     if _vjp.args[0].args != ((),):
         return False

pennylane/optimize/adaptive.py

@@ -14,7 +14,7 @@
 """Adaptive optimizer"""
 import copy
 
-# pylint: disable= no-value-for-parameter, protected-access
+# pylint: disable= no-value-for-parameter, protected-access, not-callable
 import pennylane as qml
 from pennylane import numpy as np
 

pennylane/optimize/rotoselect.py

@@ -133,6 +133,7 @@ def step(self, objective_fn, x, generators, **kwargs):
         """
         x_flat = np.fromiter(_flatten(x), dtype=float)
         # wrap the objective function so that it accepts the flattened parameter array
+        # pylint:disable=unnecessary-lambda-assignment
         objective_fn_flat = lambda x_flat, gen: objective_fn(
             unflatten(x_flat, x), generators=gen, **kwargs
         )

pennylane/qaoa/cost.py

@@ -15,6 +15,7 @@
 Methods for generating QAOA cost Hamiltonians corresponding to
 different optimization problems.
 """
+# pylint: disable=unnecessary-lambda-assignment
 from typing import Iterable, Union
 import networkx as nx
 import retworkx as rx

pennylane/qaoa/cycle.py

@@ -14,7 +14,7 @@
 r"""
 Functionality for finding the maximum weighted cycle of directed graphs.
 """
-# pylint: disable=unnecessary-comprehension
+# pylint: disable=unnecessary-comprehension, unnecessary-lambda-assignment
 import itertools
 from typing import (
     Dict,

pennylane/qaoa/mixers.py

@@ -14,6 +14,7 @@
 r"""
 Methods for constructing QAOA mixer Hamiltonians.
 """
+# pylint: disable=unnecessary-lambda-assignment
 import itertools
 import functools
 from typing import Iterable, Union

pennylane/templates/layers/particle_conserving_u2.py

@@ -217,8 +217,8 @@ def compute_decomposition(weights, wires, init_state):  # pylint: disable=argume
 
         for l in range(n_layers):
 
-            for j, _ in enumerate(wires):
-                op_list.append(qml.RZ(weights[l, j], wires=wires[j]))
+            for j, wires_ in enumerate(wires):
+                op_list.append(qml.RZ(weights[l, j], wires=wires_))
 
             for i, wires_ in enumerate(nm_wires):
                 op_list.extend(u2_ex_gate(weights[l, len(wires) + i], wires=wires_))

tests/data/test_dataset_access.py

@@ -54,6 +54,7 @@ def httpserver_listen_address():
     return ("localhost", 8888)
 
 
+# pylint:disable=unused-argument
 def get_mock(url, timeout=1.0):
     """Return the foldermap or data_struct according to URL"""
     resp = MagicMock(ok=True)
@@ -70,6 +71,7 @@ def submit_download_mock(_self, _fetch_and_save, filename, dest_folder):
     qml.data.Dataset._write_file(content, os.path.join(dest_folder, filename))
 
 
+# pylint:disable=unused-argument
 def wait_mock_fixture(_futures, return_when=None):
     """Patch to avoid raising exceptions after collecting threads."""
     return MagicMock(done=[])
@@ -605,7 +607,7 @@ class TestLoadInteractive:
     )
     def test_load_interactive_success(
         self, mock_input, mock_load, mock_sleep, side_effect, data_name, kwargs, sleep_call_count
-    ):
+    ):  # pylint:disable=too-many-arguments
         """Test that load_interactive succeeds."""
         mock_input.side_effect = side_effect
         assert isinstance(qml.data.load_interactive(), qml.data.Dataset)