Issue #6551: test_zipimport could import and then destroy some modules of

the encodings package, which would make other tests fail further down
the road because the internally cached encoders and decoders would point
to empty global variables.

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/test/support.py b/Lib/test/support.py
index 0c69aac6de..7b0241aacc 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -951,6 +951,23 @@ def run_doctest(module, verbosity=None):
               (module.__name__, t))
     return f, t
 
+
+#=======================================================================
+# Support for saving and restoring the imported modules.
+
+def modules_setup():
+    return sys.modules.copy(),
+
+def modules_cleanup(oldmodules):
+    # Encoders/decoders are registered permanently within the internal
+    # codec cache. If we destroy the corresponding modules their
+    # globals will be set to None which will trip up the cached functions.
+    encodings = [(k, v) for k, v in sys.modules.items()
+                 if k.startswith('encodings.')]
+    sys.modules.clear()
+    sys.modules.update(encodings)
+    sys.modules.update(oldmodules)
+
 #=======================================================================
 # Threading support to prevent reporting refleaks when running regrtest.py -R