Serialize Checkers PluginTypeManager to a dict

It seems likely that the multiprocessing module on Windows is not
capable of serializing an object with the structure that we have and
preserving the attributes we dynamically set on plugins (like the
FlakesChecker). To avoid issues like this with all plugins (although
we have only found this on Windows with the FlakesChecker), let's try
serializing the Checkers PluginTypeManager to a dictionary so that the
only object that a Queue is really trying to serialize/deserialize is
the FlakesChecker itself.

Related to #179

2 files changed, 12 insertions, 2 deletions

diff --git a/tests/integration/test_checker.py b/tests/integration/test_checker.py
index 5c013b6..1b8a3c5 100644
--- a/tests/integration/test_checker.py
+++ b/tests/integration/test_checker.py
@@ -63,7 +63,11 @@ def test_handle_file_plugins(plugin_target):
     # Prevent it from reading lines from stdin or somewhere else
     with mock.patch('flake8.processor.FileProcessor.read_lines',
                     return_value=['Line 1']):
-        file_checker = checker.FileChecker('-', checks, mock.MagicMock())
+        file_checker = checker.FileChecker(
+            '-',
+            checks.to_dictionary(),
+            mock.MagicMock()
+        )
 
     # Do not actually build an AST
     file_checker.processor.build_ast = lambda: True
diff --git a/tests/unit/test_checker_manager.py b/tests/unit/test_checker_manager.py
index 7e9c5b1..e5562ef 100644
--- a/tests/unit/test_checker_manager.py
+++ b/tests/unit/test_checker_manager.py
@@ -47,8 +47,14 @@ def test_make_checkers():
     """Verify that we create a list of FileChecker instances."""
     style_guide = style_guide_mock()
     files = ['file1', 'file2']
+    checkplugins = mock.Mock()
+    checkplugins.to_dictionary.return_value = {
+        'ast_plugins': [],
+        'logical_line_plugins': [],
+        'physical_line_plugins': [],
+    }
     with mock.patch('flake8.checker.multiprocessing', None):
-        manager = checker.Manager(style_guide, files, [])
+        manager = checker.Manager(style_guide, files, checkplugins)
 
     with mock.patch('flake8.utils.filenames_from') as filenames_from:
         filenames_from.side_effect = [['file1'], ['file2']]