Add test for broken/invalid cachefile

tsstats/tests/test_cache.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 import os
 import shutil
+from pickle import UnpicklingError
 
 import pytest
 
@@ -64,6 +65,11 @@ def test_cache_needs_parsing(cache, tmpdir):
     assert cache.needs_parsing(tmplog_path)
 
 
+def test_cache_read_broken_file():
+    with pytest.raises(UnpicklingError):
+        Cache.read('tsstats/__init__.py')
+
+
 # INTEGRATION
 def test_cache_integration(cache_path):
     first_run = list(parse_logs(