application: Pass prelim opts and args to .make_config_finder()

Now that `.parse_preliminary_options_and_args()` returns options and
arguments, the boolean for appending configuration and the arguments can
be threaded through to the creation of the `ConfigFileFinder`.

src/flake8/api/legacy.py

@@ -32,7 +32,7 @@ def get_style_guide(**kwargs):
         []
     )
     flake8.configure_logging(prelim_opts.verbose, prelim_opts.output_file)
-    application.make_config_finder()
+    application.make_config_finder(prelim_opts.append_config, prelim_args)
     application.find_plugins()
     application.register_plugin_options()
     application.parse_configuration_and_cli([])

src/flake8/main/application.py

@@ -57,7 +57,7 @@ class Application(object):
         #: The preliminary arguments parsed from CLI before plugins are loaded
         self.prelim_args = None  # type: List[str]
         #: The instance of :class:`flake8.options.config.ConfigFileFinder`
-        self.config_finder = None
+        self.config_finder = None  # type: config.ConfigFileFinder
 
         #: The :class:`flake8.options.config.LocalPlugins` found in config
         self.local_plugins = None  # type: config.LocalPlugins
@@ -160,13 +160,18 @@ class Application(object):
                 (self.result_count > 0) or self.catastrophic_failure
             )
 
-    def make_config_finder(self):
-        """Make our ConfigFileFinder based on preliminary opts and args."""
+    def make_config_finder(self, append_config, args):
+        # type: (List[str], List[str]) -> None
+        """Make our ConfigFileFinder based on preliminary opts and args.
+
+        :param list append_config:
+            List of configuration files to be parsed for configuration.
+        :param list args:
+            The list of file arguments passed from the CLI.
+        """
         if self.config_finder is None:
             self.config_finder = config.ConfigFileFinder(
-                self.option_manager.program_name,
-                self.prelim_args,
-                self.prelim_opts.append_config,
+                self.option_manager.program_name, args, append_config
             )
 
     def find_plugins(self):
@@ -361,7 +366,7 @@ class Application(object):
             argv
         )
         flake8.configure_logging(prelim_opts.verbose, prelim_opts.output_file)
-        self.make_config_finder()
+        self.make_config_finder(prelim_opts.append_config, prelim_args)
         self.find_plugins()
         self.register_plugin_options()
         self.parse_configuration_and_cli(argv)

tests/unit/test_legacy_api.py

@@ -11,6 +11,7 @@ from flake8.formatting import base as formatter
 def test_get_style_guide():
     """Verify the methods called on our internal Application."""
     prelim_opts = argparse.Namespace(
+        append_config=[],
         output_file=None,
         verbose=0,
     )
@@ -26,7 +27,7 @@ def test_get_style_guide():
 
     application.assert_called_once_with()
     mockedapp.parse_preliminary_options_and_args.assert_called_once_with([])
-    mockedapp.make_config_finder.assert_called_once_with()
+    mockedapp.make_config_finder.assert_called_once_with([], [])
     mockedapp.find_plugins.assert_called_once_with()
     mockedapp.register_plugin_options.assert_called_once_with()
     mockedapp.parse_configuration_and_cli.assert_called_once_with([])