refactor and simplify configuration loading

tests/integration/test_aggregator.py

@@ -1,5 +1,4 @@
 """Test aggregation of config files and command-line options."""
-import argparse
 import os
 
 import pytest
@@ -9,24 +8,38 @@ from flake8.options import aggregator
 from flake8.options import config
 from flake8.options import manager
 
-CLI_SPECIFIED_CONFIG = "tests/fixtures/config_files/cli-specified.ini"
-
 
 @pytest.fixture
 def optmanager():
     """Create a new OptionManager."""
-    prelim_parser = argparse.ArgumentParser(add_help=False)
-    options.register_preliminary_options(prelim_parser)
     option_manager = manager.OptionManager(
         prog="flake8",
         version="3.0.0",
-        parents=[prelim_parser],
     )
     options.register_default_options(option_manager)
     return option_manager
 
 
-def test_aggregate_options_with_config(optmanager):
+@pytest.fixture
+def flake8_config(tmp_path):
+    cfg_s = """\
+[flake8]
+ignore =
+    E123,
+    W234,
+    E111
+exclude =
+    foo/,
+    bar/,
+    bogus/
+quiet = 1
+"""
+    cfg = tmp_path.joinpath("tox.ini")
+    cfg.write_text(cfg_s)
+    return str(cfg)
+
+
+def test_aggregate_options_with_config(optmanager, flake8_config):
     """Verify we aggregate options and config values appropriately."""
     arguments = [
         "flake8",
@@ -35,11 +48,12 @@ def test_aggregate_options_with_config(optmanager):
         "--exclude",
         "tests/*",
     ]
-    config_finder = config.ConfigFileFinder(
-        "flake8", config_file=CLI_SPECIFIED_CONFIG
-    )
+    cfg, cfg_dir = config.load_config(flake8_config, [])
     options = aggregator.aggregate_options(
-        optmanager, config_finder, arguments
+        optmanager,
+        cfg,
+        cfg_dir,
+        arguments,
     )
 
     assert options.select == ["E11", "E34", "E402", "W", "F"]
@@ -47,7 +61,7 @@ def test_aggregate_options_with_config(optmanager):
     assert options.exclude == [os.path.abspath("tests/*")]
 
 
-def test_aggregate_options_when_isolated(optmanager):
+def test_aggregate_options_when_isolated(optmanager, flake8_config):
     """Verify we aggregate options and config values appropriately."""
     arguments = [
         "flake8",
@@ -56,11 +70,9 @@ def test_aggregate_options_when_isolated(optmanager):
         "--exclude",
         "tests/*",
     ]
-    config_finder = config.ConfigFileFinder("flake8", ignore_config_files=True)
+    cfg, cfg_dir = config.load_config(flake8_config, [], isolated=True)
     optmanager.extend_default_ignore(["E8"])
-    options = aggregator.aggregate_options(
-        optmanager, config_finder, arguments
-    )
+    options = aggregator.aggregate_options(optmanager, cfg, cfg_dir, arguments)
 
     assert options.select == ["E11", "E34", "E402", "W", "F"]
     assert sorted(options.ignore) == [