issue #18698: ensure importlib.reload() returns the module out of sys.modules.

Author: ericsnowcurrently

Lib/imp.py

@@ -268,7 +268,9 @@ def reload(module):
         if parent_name and parent_name not in sys.modules:
             msg = "parent {!r} not in sys.modules"
             raise ImportError(msg.format(parent_name), name=parent_name)
-        return module.__loader__.load_module(name)
+        module.__loader__.load_module(name)
+        # The module may have replaced itself in sys.modules!
+        return sys.modules[module.__name__]
     finally:
         try:
             del _RELOADING[name]

Lib/test/test_imp.py

@@ -5,6 +5,7 @@
 import shutil
 import sys
 from test import support
+from test.test_importlib import util
 import unittest
 import warnings
 
@@ -285,6 +286,22 @@ def cleanup():
         with self.assertRaisesRegex(ImportError, 'html'):
             imp.reload(parser)
 
+    def test_module_replaced(self):
+        # see #18698
+        def code():
+            module = type(sys)('top_level')
+            module.spam = 3
+            sys.modules['top_level'] = module
+        mock = util.mock_modules('top_level',
+                                 module_code={'top_level': code})
+        with mock:
+            with util.import_state(meta_path=[mock]):
+                module = importlib.import_module('top_level')
+                reloaded = imp.reload(module)
+                actual = sys.modules['top_level']
+                self.assertEqual(actual.spam, 3)
+                self.assertEqual(reloaded.spam, 3)
+
 
 class PEP3147Tests(unittest.TestCase):
     """Tests of PEP 3147."""

Misc/NEWS

@@ -202,6 +202,8 @@ Library
 - Issue #17269: Workaround for socket.getaddrinfo crash on MacOS X
   with port None or "0" and flags AI_NUMERICSERV.
 
+- Issue #18698: Ensure imp.reload() returns the module out of sys.modules.
+
 - Issue #18080: When building a C extension module on OS X, if the compiler
   is overriden with the CC environment variable, use the new compiler as
   the default for linking if LDSHARED is not also overriden.  This restores