Fix pylint parallel execution

CONTRIBUTORS.rst

@@ -12,7 +12,7 @@ Contributors
 * Carlos Coêlho (`@chocoelho <https://github.com/chocoelho>`_)
 * Carlos Cruz (`@ccruz09 <https://github.com/ccruz09>`_)
 * Claudiu Popa (`@PCManticore <https://github.com/PCManticore>`_)
-* D Morgan (`@morgangraphics <https://github.com/morgangraphics>` _)
+* D Morgan (`@morgangraphics <https://github.com/morgangraphics>`_)
 * David J Pugh (`@djpugh <https://github.com/djpugh>`_)
 * Eric Brown (`@ericwb <https://github.com/ericwb>`_)
 * Florian Bruhin (`@The-Compiler <https://github.com/The-Compiler>`_)
@@ -25,6 +25,7 @@ Contributors
 * Luke Hinds (`@lukehinds <https://github.com/lukehinds>`_)
 * Matt Seymour (`@mattseymour <https://github.com/mattseymour>`_)
 * Michael Tinsley (`@michaeltinsley <https://github.com/michaeltinsley>`_)
+* Michal Petrucha (`@koniiiik <https://github.com/koniiiik>`_)
 * Phil Frost (`@bitglue <https://github.com/bitglue>`_)
 * Phil Jones (`@pgjones <https://github.com/pgjones>`_)
 * Pierre Sassoulas (`@Pierre-Sassoulas <https://github.com/Pierre-Sassoulas>`_)

prospector/config/__init__.py

@@ -40,14 +40,20 @@ def __init__(self, workdir: Path = None):
         self.messages: List[Message] = []
 
     def make_exclusion_filter(self):
+        # Only close over the attributes required by the filter, rather
+        # than the entire self, because ProspectorConfig can't be pickled
+        # because of the config attribute, which would break parallel
+        # pylint.
+        ignores, workdir = self.ignores, self.workdir
+
         def _filter(path: Path):
-            for ignore in self.ignores:
+            for ignore in ignores:
                 # first figure out where the path is, relative to the workdir
                 # ignore-paths/patterns will usually be relative to a repository
                 # root or the CWD, but the path passed to prospector may not be
                 path = path.resolve().absolute()
-                if is_relative_to(path, self.workdir):
-                    path = path.relative_to(self.workdir)
+                if is_relative_to(path, workdir):
+                    path = path.relative_to(workdir)
                 if ignore.match(str(path)):
                     return True
             return False

pyproject.toml

@@ -38,7 +38,7 @@ include = [
 prospector = 'prospector.run:main'
 
 [tool.poetry.dependencies]
-python = ">=3.7,<4.0"
+python = ">=3.7.2,<4.0"
 pylint = ">=2.8.3"
 pylint-celery = "0.3"
 pylint-django = "~2.5"

tests/tools/pylint/parallel/.prospector.yml

@@ -0,0 +1,5 @@
+max-line-length: 40
+
+pylint:
+  options:
+    jobs: 2

tests/tools/pylint/parallel/one.py

@@ -0,0 +1,2 @@
+def this_is_a_line_that_is_longer_than_40_characters():
+    return "hi"

tests/tools/pylint/test_pylint_tool.py

@@ -20,9 +20,9 @@ def _get_pylint_tool_and_prospector_config(argv_patch=None) -> Tuple[PylintTool,
     return pylint_tool, config
 
 
-def _get_test_files(*names: str):
+def _get_test_files(*names: str, exclusion_filters=None):
     paths = [THIS_DIR / name for name in names]
-    return FileFinder(*paths)
+    return FileFinder(*paths, exclusion_filters=exclusion_filters)
 
 
 class TestPylintTool(TestCase):
@@ -95,3 +95,17 @@ def test_will_throw_useless_suppression(self):
         assert any(
             m.code == "useless-suppression" for m in messages
         ), "There should be at least one useless suppression"
+
+    def test_parallel_execution(self):
+        root = THIS_DIR / "parallel"
+
+        with patch("pathlib.Path.cwd", return_value=root.absolute()):
+            pylint_tool, config = _get_pylint_tool_and_prospector_config()
+        self.assertEqual(Path(config.workdir).absolute(), root.absolute())
+
+        found_files = _get_test_files(root, exclusion_filters=[config.make_exclusion_filter()])
+        pylint_tool.configure(config, found_files)
+        assert pylint_tool._linter.config.jobs == 2
+
+        messages = pylint_tool.run(found_files)
+        assert "line-too-long" in [msg.code for msg in messages if msg.source == "pylint"]