Add support for local (in-repo, non-setuptools) plugins.

Closes #357

tests/unit/test_get_local_plugins.py

@@ -0,0 +1,38 @@
+"""Tests for get_local_plugins."""
+import mock
+
+from flake8.options import config
+
+
+def test_get_local_plugins_respects_isolated():
+    """Verify behaviour of get_local_plugins with isolated=True."""
+    config_finder = mock.MagicMock()
+
+    local_plugins = config.get_local_plugins(config_finder, isolated=True)
+
+    assert local_plugins.extension == []
+    assert local_plugins.report == []
+    assert config_finder.local_configs.called is False
+    assert config_finder.user_config.called is False
+
+
+def test_get_local_plugins_uses_cli_config():
+    """Verify behaviour of get_local_plugins with a specified config."""
+    config_finder = mock.MagicMock()
+
+    config.get_local_plugins(config_finder, cli_config='foo.ini')
+
+    config_finder.cli_config.assert_called_once_with('foo.ini')
+
+
+def test_get_local_plugins():
+    """Verify get_local_plugins returns expected plugins."""
+    config_fixture_path = 'tests/fixtures/config_files/local-plugin.ini'
+    config_finder = config.ConfigFileFinder('flake8', [], [])
+
+    with mock.patch.object(config_finder, 'local_config_files') as localcfs:
+        localcfs.return_value = [config_fixture_path]
+        local_plugins = config.get_local_plugins(config_finder)
+
+    assert local_plugins.extension == ['XE = test_plugins:ExtensionTestPlugin']
+    assert local_plugins.report == ['XR = test_plugins:ReportTestPlugin']