Re-allow for relative paths for exclude

Previously, all testing was done from the directory in which the
configuration file lived, so this bug went unnoticed. However, if you
run Flake8 against its own source from a directory above, you would
notice that the patterns in the exclude config value in tox.ini were
ignored. This is because we (like any reasonable person) are using
relative paths. The path is relative, however, to the directory in
which the configuration file was located. So we keep track of which
directory that is and use that to normalize the paths in the config
file.

Yes, there is an unrelated change to our tox.ini in this commit as
well. ;-)

Closes #194

docs/source/release-notes/3.0.3.rst

@@ -4,21 +4,25 @@
 - Disable ``--jobs`` for any version of Python on Windows.
   (See also `this Python bug report`_)
 
-- Fix ``# noqa`` comments followed by a ``:`` and explanation broken by
-  3.0.0 (See also `GitLab#178`_)
-
-- Fix issue where users were unable to ignore plugin errors that were on
-  by default. (See also `GitLab#195`_)
-
 - Raise exception when entry_point in plugin not callable.
   This raises an informative error when a plugin fails to load because its
   entry_point is not callable, which can happen with a plugin which is buggy or
   not updated for the current version of flake8. This is nicer than raising a
   `PicklingError` about failing to pickle a module (See also `GitLab#164`_)
 
+- Fix ``# noqa`` comments followed by a ``:`` and explanation broken by
+  3.0.0 (See also `GitLab#178`_)
+
 - Always open our output file in append mode so we do not overwrite log
   messages. (See also `GitLab#193`_)
 
+- When normalizing path values read from configuration, keep in context the
+  directory where the configuration was found so that relative paths work.
+  (See also `GitLab#194`_)
+
+- Fix issue where users were unable to ignore plugin errors that were on
+  by default. (See also `GitLab#195`_)
+
 
 .. links
 .. _GitLab#164:
@@ -27,6 +31,8 @@
     https://gitlab.com/pycqa/flake8/issues/178
 .. _GitLab#193:
     https://gitlab.com/pycqa/flake8/issues/193
+.. _GitLab#194:
+    https://gitlab.com/pycqa/flake8/issues/193
 .. _GitLab#195:
     https://gitlab.com/pycqa/flake8/issues/195
 .. _this Python bug report:

src/flake8/options/config.py

@@ -43,6 +43,8 @@ class ConfigFileFinder(object):
         # List of filenames to find in the local/project directory
         self.project_filenames = ('setup.cfg', 'tox.ini', self.program_config)
 
+        self.local_directory = os.path.abspath(os.curdir)
+
         if not args:
             args = ['.']
         self.parent = self.tail = os.path.abspath(os.path.commonprefix(args))
@@ -78,6 +80,7 @@ class ConfigFileFinder(object):
                 if os.path.exists(filename):
                     yield filename
                     found_config_files = True
+                    self.local_directory = parent
             (parent, tail) = os.path.split(parent)
 
     def local_config_files(self):
@@ -160,9 +163,11 @@ class MergedConfigParser(object):
         self.config_finder = ConfigFileFinder(self.program_name, self.args,
                                               self.extra_config_files)
 
-    @staticmethod
-    def _normalize_value(option, value):
-        final_value = option.normalize(value)
+    def _normalize_value(self, option, value):
+        final_value = option.normalize(
+            value,
+            self.config_finder.local_directory,
+        )
         LOG.debug('%r has been normalized to %r for option "%s"',
                   value, final_value, option.config_name)
         return final_value

src/flake8/options/manager.py

@@ -121,14 +121,14 @@ class Option(object):
             return self.long_option_name[2:].replace('-', '_')
         return self.short_option_name[1]
 
-    def normalize(self, value):
+    def normalize(self, value, *normalize_args):
         """Normalize the value based on the option configuration."""
         if self.normalize_paths:
             # Decide whether to parse a list of paths or a single path
             normalize = utils.normalize_path
             if self.comma_separated_list:
                 normalize = utils.normalize_paths
-            return normalize(value)
+            return normalize(value, *normalize_args)
         elif self.comma_separated_list:
             return utils.parse_comma_separated_list(value)
         return value

tox.ini

@@ -138,10 +138,18 @@ commands =
 # Once Flake8 3.0 is released and in a good state, we can use both and it will
 # work well \o/
 ignore = D203
-# NOTE(sigmavirus24): Once we release 3.0.0 this exclude option can be specified
-# across multiple lines. Presently it cannot be specified across multiple lines.
-# :-(
-exclude = .tox,.git,__pycache__,docs/source/conf.py,build,dist,tests/fixtures/*,*.pyc,*.egg-info,./.cache,./.eggs
+exclude =
+    .tox,
+    .git,
+    __pycache__,
+    docs/source/conf.py,
+    build,
+    dist,
+    tests/fixtures/*,
+    *.pyc,
+    *.egg-info,
+    .cache,
+    .eggs
 max-complexity = 10
 import-order-style = google
 application-import-names = flake8