Cleanup: fix mypy errors

This mostly handles a mypy change where implicit optionals (i.e. things
like `size: int = None`) are no longer allowed.

No functional changes.

tests/abstract_test.py

@@ -20,6 +20,7 @@
 import logging
 import pathlib
 import unittest
+from typing import Optional
 
 from blender_asset_tracer import blendfile
 
@@ -29,6 +30,9 @@ logging.basicConfig(
 
 
 class AbstractBlendFileTest(unittest.TestCase):
+    blendfiles: pathlib.Path
+    bf: Optional[blendfile.BlendFile]
+
     @classmethod
     def setUpClass(cls):
         cls.blendfiles = pathlib.Path(__file__).with_name("blendfiles")

tests/test_shaman_transfer.py

@@ -19,6 +19,7 @@
 # (c) 2019, Blender Foundation - Sybren A. Stüvel
 import pathlib
 import platform
+from typing import Dict
 
 import responses
 
@@ -29,6 +30,12 @@ httpmock = responses.RequestsMock()
 
 
 class ShamanTransferTest(AbstractBlendFileTest):
+    test_file1: pathlib.Path
+    test_file2: pathlib.Path
+    expected_checksums: Dict[pathlib.Path, str]
+    file_sizes: Dict[pathlib.Path, int]
+    packed_names: Dict[pathlib.Path, str]
+
     @classmethod
     def setUpClass(cls):
         super().setUpClass()

tests/test_tracer.py

@@ -2,6 +2,7 @@ import collections
 import logging
 import sys
 import typing
+from typing import Optional
 
 from blender_asset_tracer import trace, blendfile
 from blender_asset_tracer.blendfile import dna
@@ -65,7 +66,7 @@ class AssetHoldingBlocksTest(AbstractTracerTest):
 
 class DepsTest(AbstractTracerTest):
     @staticmethod
-    def field_name(field: dna.Field) -> typing.Optional[str]:
+    def field_name(field: Optional[dna.Field]) -> typing.Optional[str]:
         if field is None:
             return None
         return field.name.name_full.decode()
@@ -88,18 +89,18 @@ class DepsTest(AbstractTracerTest):
 
             exp = expects.get(dep.block_name, None)
             if isinstance(exp, (set, list)):
-                self.assertIn(actual, exp, msg="for block %s" % dep.block_name)
+                self.assertIn(actual, exp, msg="for block %r" % dep.block_name)
                 exp.remove(actual)
                 if not exp:
                     # Don't leave empty sets in expects.
                     del expects[dep.block_name]
             elif exp is None:
                 self.assertIsNone(
-                    actual, msg="unexpected dependency of block %s" % dep.block_name
+                    actual, msg="unexpected dependency of block %r" % dep.block_name
                 )
                 del expects[dep.block_name]
             else:
-                self.assertEqual(exp, actual, msg="for block %s" % dep.block_name)
+                self.assertEqual(exp, actual, msg="for block %r" % dep.block_name)
                 del expects[dep.block_name]
 
         # All expected uses should have been seen.