Start testing MergedConfigParser

Rename the GETINT/GETBOOL sets on the MergedConfigParser to use better
names.

tests/unit/test_merged_config_parser.py

@@ -0,0 +1,41 @@
+"""Unit tests for flake8.options.config.MergedConfigParser."""
+import mock
+import pytest
+
+from flake8.options import config
+from flake8.options import manager
+
+
+@pytest.fixture
+def optmanager():
+    return manager.OptionManager(prog='flake8', version='3.0.0a1')
+
+
+@pytest.mark.parametrize('args,extra_config_files', [
+    (None, None),
+    (None, []),
+    (None, ['foo.ini']),
+    ('flake8/', []),
+    ('flake8/', ['foo.ini']),
+])
+def test_creates_its_own_config_file_finder(args, extra_config_files,
+                                            optmanager):
+    """Verify we create a ConfigFileFinder correctly."""
+    class_path = 'flake8.options.config.ConfigFileFinder'
+    with mock.patch(class_path) as ConfigFileFinder:
+        parser = config.MergedConfigParser(
+            option_manager=optmanager,
+            extra_config_files=extra_config_files,
+            args=args,
+        )
+
+    assert parser.program_name == 'flake8'
+    ConfigFileFinder.assert_called_once_with(
+        'flake8',
+        args,
+        extra_config_files or [],
+    )
+
+
+def test_parse_cli_config(optmanager):
+    pass