Merge branch 'app-make-config-side-effect-free' into 'master'

application: Change `make_config_finder` to be a pure static method

See merge request pycqa/flake8!378

3 files changed, 18 insertions, 8 deletions

diff --git a/src/flake8/api/legacy.py b/src/flake8/api/legacy.py
index 6fa13b4..b8c69c5 100644
--- a/src/flake8/api/legacy.py
+++ b/src/flake8/api/legacy.py
@@ -30,7 +30,9 @@ def get_style_guide(**kwargs):
     application = app.Application()
     prelim_opts, remaining_args = application.parse_preliminary_options([])
     flake8.configure_logging(prelim_opts.verbose, prelim_opts.output_file)
-    application.make_config_finder(prelim_opts.append_config)
+    application.config_finder = application.make_config_finder(
+        application.program, prelim_opts.append_config
+    )
     application.find_plugins(prelim_opts.config, prelim_opts.isolated)
     application.register_plugin_options()
     application.parse_configuration_and_cli(remaining_args)
diff --git a/src/flake8/main/application.py b/src/flake8/main/application.py
index 40e196c..a317144 100644
--- a/src/flake8/main/application.py
+++ b/src/flake8/main/application.py
@@ -133,17 +133,22 @@ class Application(object):
                 (self.result_count > 0) or self.catastrophic_failure
             )
 
-    def make_config_finder(self, extra_config_files):
-        # type: (List[str]) -> None
+    @staticmethod
+    def make_config_finder(program_name, extra_config_files):
+        # type: (str, List[str]) -> config.ConfigFileFinder
         """Make our ConfigFileFinder based on preliminary options.
 
+        :param str program_name:
+            Name of the current programin (e.g., flake8).
         :param list extra_config_files:
             List of addtional configuration files to be parsed for
             configuration.
+        :returns:
+            The configuration file finder
+        :rtype:
+            config.ConfigFileFinder
         """
-        self.config_finder = config.ConfigFileFinder(
-            self.program, extra_config_files
-        )
+        return config.ConfigFileFinder(program_name, extra_config_files)
 
     def find_plugins(self, config_file, ignore_config_files):
         # type: (Optional[str], bool) -> None
@@ -333,7 +338,9 @@ class Application(object):
         # our legacy API calls to these same methods.
         prelim_opts, remaining_args = self.parse_preliminary_options(argv)
         flake8.configure_logging(prelim_opts.verbose, prelim_opts.output_file)
-        self.make_config_finder(prelim_opts.append_config)
+        self.config_finder = self.make_config_finder(
+            self.program, prelim_opts.append_config
+        )
         self.find_plugins(prelim_opts.config, prelim_opts.isolated)
         self.register_plugin_options()
         self.parse_configuration_and_cli(remaining_args)
diff --git a/tests/unit/test_legacy_api.py b/tests/unit/test_legacy_api.py
index 071bcf3..77d9020 100644
--- a/tests/unit/test_legacy_api.py
+++ b/tests/unit/test_legacy_api.py
@@ -19,13 +19,14 @@ def test_get_style_guide():
     )
     mockedapp = mock.Mock()
     mockedapp.parse_preliminary_options.return_value = (prelim_opts, [])
+    mockedapp.program = 'flake8'
     with mock.patch('flake8.main.application.Application') as application:
         application.return_value = mockedapp
         style_guide = api.get_style_guide()
 
     application.assert_called_once_with()
     mockedapp.parse_preliminary_options.assert_called_once_with([])
-    mockedapp.make_config_finder.assert_called_once_with([])
+    mockedapp.make_config_finder.assert_called_once_with(mockedapp.program, [])
     mockedapp.find_plugins.assert_called_once_with(None, False)
     mockedapp.register_plugin_options.assert_called_once_with()
     mockedapp.parse_configuration_and_cli.assert_called_once_with([])