Add the ability to skip checking some functions.

There are times when you might not want to check a function's
docstring.  Specifically, we frequently want to ignore
test files.  There is already an exemption that causes test
functions to be considered non-public.  This extends on
that idea and makes it configurable so a user can cause
a test function to be allowed to have no docstring.

Author: mgilson-argo

Diff for: src/pydocstyle/checker.py

@@ -136,6 +136,7 @@ def check_source(
         ignore_decorators=None,
         property_decorators=None,
         ignore_inline_noqa=False,
+        ignore_functions=None,
     ):
         self.property_decorators = (
             {} if property_decorators is None else property_decorators
@@ -150,9 +151,19 @@ def check_source(
                         len(ignore_decorators.findall(dec.name)) > 0
                         for dec in definition.decorators
                     )
+                    # Only skip checking the docstring if absent.
+                    # If the docstring is present, then check it as normal
+                    name_skip = (
+                        ignore_functions is not None
+                        and not definition.docstring
+                        and bool(ignore_functions.findall(definition.name))
+                    )
+
                     if (
-                        ignore_inline_noqa or not skipping_all
-                    ) and not decorator_skip:
+                        (ignore_inline_noqa or not skipping_all)
+                        and not decorator_skip
+                        and not name_skip
+                    ):
                         error = this_check(
                             self, definition, definition.docstring
                         )
@@ -1088,6 +1099,7 @@ def check(
     ignore_decorators=None,
     property_decorators=None,
     ignore_inline_noqa=False,
+    ignore_functions=None,
 ):
     """Generate docstring errors that exist in `filenames` iterable.
 
@@ -1141,9 +1153,10 @@ def check(
             for error in ConventionChecker().check_source(
                 source,
                 filename,
-                ignore_decorators,
-                property_decorators,
-                ignore_inline_noqa,
+                ignore_decorators=ignore_decorators,
+                property_decorators=property_decorators,
+                ignore_inline_noqa=ignore_inline_noqa,
+                ignore_functions=ignore_functions,
             ):
                 code = getattr(error, 'code', None)
                 if code in checked_codes:

Diff for: src/pydocstyle/cli.py

@@ -43,13 +43,15 @@ def run_pydocstyle():
             checked_codes,
             ignore_decorators,
             property_decorators,
+            ignore_functions,
         ) in conf.get_files_to_check():
             errors.extend(
                 check(
                     (filename,),
                     select=checked_codes,
                     ignore_decorators=ignore_decorators,
                     property_decorators=property_decorators,
+                    ignore_functions=ignore_functions,
                 )
             )
     except IllegalConfiguration as error:

Diff for: src/pydocstyle/config.py

@@ -180,6 +180,7 @@ class ConfigurationParser:
         'match',
         'match-dir',
         'ignore-decorators',
+        'ignore-functions',
     )
     BASE_ERROR_SELECTION_OPTIONS = ('ignore', 'select', 'convention')
 
@@ -189,6 +190,7 @@ class ConfigurationParser:
     DEFAULT_PROPERTY_DECORATORS = (
         "property,cached_property,functools.cached_property"
     )
+    DEFAULT_IGNORE_FUNCTIONS_RE = ''
     DEFAULT_CONVENTION = conventions.pep257
 
     PROJECT_CONFIG_FILES = (
@@ -263,6 +265,10 @@ def _get_matches(conf):
             match_dir_func = re(conf.match_dir + '$').match
             return match_func, match_dir_func
 
+        def _get_ignore_functions(conf):
+            """Return the `ignore_functions` as None or regex."""
+            return re(conf.ignore_functions) if conf.ignore_functions else None
+
         def _get_ignore_decorators(conf):
             """Return the `ignore_decorators` as None or regex."""
             return (
@@ -284,6 +290,7 @@ def _get_property_decorators(conf):
                     match, match_dir = _get_matches(config)
                     ignore_decorators = _get_ignore_decorators(config)
                     property_decorators = _get_property_decorators(config)
+                    ignore_functions = _get_ignore_functions(config)
 
                     # Skip any dirs that do not match match_dir
                     dirs[:] = [d for d in dirs if match_dir(d)]
@@ -296,18 +303,22 @@ def _get_property_decorators(conf):
                                 list(config.checked_codes),
                                 ignore_decorators,
                                 property_decorators,
+                                ignore_functions,
                             )
             else:
                 config = self._get_config(os.path.abspath(name))
                 match, _ = _get_matches(config)
                 ignore_decorators = _get_ignore_decorators(config)
                 property_decorators = _get_property_decorators(config)
+                ignore_functions = _get_ignore_functions(config)
+
                 if match(os.path.basename(name)):
                     yield (
                         name,
                         list(config.checked_codes),
                         ignore_decorators,
                         property_decorators,
+                        ignore_functions,
                     )
 
     # --------------------------- Private Methods -----------------------------
@@ -509,6 +520,7 @@ def _merge_configuration(self, parent_config, child_options):
             'match_dir',
             'ignore_decorators',
             'property_decorators',
+            'ignore_functions',
         ):
             kwargs[key] = getattr(child_options, key) or getattr(
                 parent_config, key
@@ -548,6 +560,7 @@ def _create_check_config(cls, options, use_defaults=True):
             'match_dir': "MATCH_DIR_RE",
             'ignore_decorators': "IGNORE_DECORATORS_RE",
             'property_decorators': "PROPERTY_DECORATORS",
+            'ignore_functions': "IGNORE_FUNCTIONS_RE",
         }
         for key, default in defaults.items():
             kwargs[key] = (
@@ -780,9 +793,10 @@ def _create_option_parser(cls):
             OptionGroup(
                 parser,
                 'Note',
-                'When using --match, --match-dir or --ignore-decorators consider '
-                'whether you should use a single quote (\') or a double quote ("), '
-                'depending on your OS, Shell, etc.',
+                'When using --match, --match-dir, --ignore-decorators or '
+                '--ignore-functions consider whether you should use a single '
+                'quote (\') or a double quote ("), depending on your OS, '
+                'Shell, etc.',
             )
         )
 
@@ -899,6 +913,19 @@ def _create_option_parser(cls):
             ),
         )
 
+        # Function selection
+        option(
+            '--ignore-functions',
+            metavar='<functions>',
+            default=None,
+            help=(
+                "ignore any functions or methods whose names fit "
+                "the <functions> regular expression; default is "
+                "--ignore-functions='{}' which does not ignore any "
+                "functions.".format(cls.DEFAULT_IGNORE_DECORATORS_RE)
+            ),
+        )
+
         return parser
 
 
@@ -911,6 +938,7 @@ def _create_option_parser(cls):
         'match_dir',
         'ignore_decorators',
         'property_decorators',
+        'ignore_functions',
     ),
 )
 

Diff for: src/tests/test_cases/functions.py

@@ -75,3 +75,21 @@ class inner():
 def func_with_weird_backslash():
     """Test a function with a weird backslash.\
 """
+
+
+def ignored_function():
+    # This function does not need a docstring
+    # because the name matches "ignored_function.*"
+    pass
+
+
+def ignored_function_with_suffix():
+    # This function does not need a docstring
+    # because the name matches "ignored_function.*"
+    pass
+
+
+@expect('D103: Missing docstring in public function')
+def missing_docstring_function():
+    # This function should have a docstring.
+    pass

Diff for: src/tests/test_definitions.py

@@ -44,6 +44,7 @@ def test_complex_file(test_case):
             select=set(ErrorRegistry.get_error_codes()),
             ignore_decorators=re.compile('wraps|ignored_decorator'),
             property_decorators=DEFAULT_PROPERTY_DECORATORS,
+            ignore_functions=re.compile("ignored_function.*"),
         )
     )
     for error in results: