Fix packaging deprecation and flake8 regression in tests (#156)

Author: MatthijsBurgh

test/spell_check.words

@@ -19,6 +19,7 @@ findtext
 getaffinity
 github
 https
+importorskip
 iterdir
 kazys
 kislyuk
@@ -28,6 +29,7 @@ lstrip
 makefile
 makefiles
 makeflags
+minversion
 modline
 monkeypatch
 msbuild

test/test_parse_cmake_version.py

@@ -2,9 +2,14 @@
 # Licensed under the Apache License, Version 2.0
 
 from colcon_cmake.task.cmake import _parse_cmake_version_string
+import pytest
 
 
 def test_parse_cmake_version():
+    # This test requires packaging v17 or newer, but the underlying code
+    # is more flexible.
+    pytest.importorskip('packaging', minversion='17')
+
     # Build version prefix string closely matching what cmake version outputs.
     base_prefix = 'cmake version '
 
@@ -33,7 +38,7 @@ def test_parse_cmake_version():
             # Input string was garbage. Assert parsing failed.
             assert parsed_version is None
         else:
-            assert parsed_version._version.release[0:3] == expected_version
+            assert parsed_version.release[0:3] == expected_version
 
 
 if __name__ == '__main__':

test/test_spell_check.py

@@ -10,7 +10,6 @@
 
 @pytest.fixture(scope='module')
 def known_words():
-    global spell_check_words_path
     return spell_check_words_path.read_text().splitlines()