bpo-25872: Add unit tests for linecache and threading

Lib/test/test_linecache.py

@@ -239,5 +239,47 @@ def raise_memoryerror(*args, **kwargs):
  self.assertEqual(linecache.getlines(FILENAME), lines)
 
 
+class LineCacheInvalidationTests(unittest.TestCase):
+ def setUp(self):
+ super().setUp()
+ linecache.clearcache()
+ self.deleted_file = os_helper.TESTFN + '.1'
+ self.modified_file = os_helper.TESTFN + '.2'
+ self.unchanged_file = os_helper.TESTFN + '.3'
+
+ for fname in (self.deleted_file,
+ self.modified_file,
+ self.unchanged_file):
+ self.addCleanup(os_helper.unlink, fname)
+ with open(fname, 'w', encoding='utf-8') as source:
+ source.write(f'print("I am{fname}")')
+
+ self.assertNotIn(fname, linecache.cache)
+ linecache.getlines(fname)
+ self.assertIn(fname, linecache.cache)
+
+ os.remove(self.deleted_file)
+ with open(self.modified_file, 'w', encoding='utf-8') as source:
+ source.write('print("was modified")')
+
+ def test_checkcache_for_deleted_file(self):
+ linecache.checkcache(self.deleted_file)
+ self.assertNotIn(self.deleted_file, linecache.cache)
+ self.assertIn(self.modified_file, linecache.cache)
+ self.assertIn(self.unchanged_file, linecache.cache)
+
+ def test_checkcache_for_modified_file(self):
+ linecache.checkcache(self.modified_file)
+ self.assertIn(self.deleted_file, linecache.cache)
+ self.assertNotIn(self.modified_file, linecache.cache)
+ self.assertIn(self.unchanged_file, linecache.cache)
+
+ def test_checkcache_with_no_parameter(self):
+ linecache.checkcache()
+ self.assertNotIn(self.deleted_file, linecache.cache)
+ self.assertNotIn(self.modified_file, linecache.cache)
+ self.assertIn(self.unchanged_file, linecache.cache)
+
+
 if __name__ == "__main__":
  unittest.main()

Lib/test/test_threading.py

@@ -4,7 +4,7 @@
 
 import test.support
 from test.support import threading_helper
-from test.support import verbose, cpython_only
+from test.support import verbose, cpython_only, os_helper
 from test.support.import_helper import import_module
 from test.support.script_helper import assert_python_ok, assert_python_failure
 
@@ -19,6 +19,7 @@
 import subprocess
 import signal
 import textwrap
+import traceback
 
 from unittest import mock
 from test import lock_tests
@@ -1345,6 +1346,22 @@ def run(self):
  # explicitly break the reference cycle to not leak a dangling thread
  thread.exc = None
 
+ def test_multithread_modify_file_noerror(self):
+ # See issue25872
+ def modify_file():
+ with open(os_helper.TESTFN, 'w', encoding='utf-8') as fp:
+ fp.write(' ')
+ traceback.format_stack()
+
+ self.addCleanup(os_helper.unlink, os_helper.TESTFN)
+ threads = [
+ threading.Thread(target=modify_file)
+ for i in range(100)
+ ]
+ for t in threads:
+ t.start()
+ t.join()
+
 
 class ThreadRunFail(threading.Thread):
  def run(self):