Issue 5354: Change API for import_fresh_module() to better support test_warnings use case (also fixes some bugs in the original implementation)
diff --git a/Lib/test/test_heapq.py b/Lib/test/test_heapq.py
index 625852d..7e3c7a1 100644
--- a/Lib/test/test_heapq.py
+++ b/Lib/test/test_heapq.py
@@ -8,7 +8,7 @@
# We do a bit of trickery here to be able to test both the C implementation
# and the Python implementation of the module.
import heapq as c_heapq
-py_heapq = test_support.import_fresh_module('heapq', ['_heapq'])
+py_heapq = test_support.import_fresh_module('heapq', blocked=['_heapq'])
class TestHeap(unittest.TestCase):
module = None
diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
index f77df70..5973e07 100644
--- a/Lib/test/test_support.py
+++ b/Lib/test/test_support.py
@@ -70,12 +70,43 @@
raise unittest.SkipTest(str(msg))
-def import_fresh_module(name, blocked_names=None, deprecated=False):
+def _save_and_remove_module(name, orig_modules):
+ """Helper function to save and remove a module from sys.modules
+
+ Return value is True if the module was in sys.modules and
+ False otherwise."""
+ saved = True
+ try:
+ orig_modules[name] = sys.modules[name]
+ except KeyError:
+ saved = False
+ else:
+ del sys.modules[name]
+ return saved
+
+
+def _save_and_block_module(name, orig_modules):
+ """Helper function to save and block a module in sys.modules
+
+ Return value is True if the module was in sys.modules and
+ False otherwise."""
+ saved = True
+ try:
+ orig_modules[name] = sys.modules[name]
+ except KeyError:
+ saved = False
+ sys.modules[name] = 0
+ return saved
+
+
+def import_fresh_module(name, fresh=(), blocked=(), deprecated=False):
"""Imports and returns a module, deliberately bypassing the sys.modules cache
and importing a fresh copy of the module. Once the import is complete,
the sys.modules cache is restored to its original state.
- Importing of modules named in blocked_names is prevented while the fresh import
+ Modules named in fresh are also imported anew if needed by the import.
+
+ Importing of modules named in blocked is prevented while the fresh import
takes place.
If deprecated is True, any module or package deprecation messages
@@ -83,21 +114,24 @@
# NOTE: test_heapq and test_warnings include extra sanity checks to make
# sure that this utility function is working as expected
with _ignore_deprecated_imports(deprecated):
- if blocked_names is None:
- blocked_names = ()
+ # Keep track of modules saved for later restoration as well
+ # as those which just need a blocking entry removed
orig_modules = {}
- if name in sys.modules:
- orig_modules[name] = sys.modules[name]
- del sys.modules[name]
+ names_to_remove = []
+ _save_and_remove_module(name, orig_modules)
try:
- for blocked in blocked_names:
- orig_modules[blocked] = sys.modules[blocked]
- sys.modules[blocked] = 0
- py_module = importlib.import_module(name)
+ for fresh_name in fresh:
+ _save_and_remove_module(fresh_name, orig_modules)
+ for blocked_name in blocked:
+ if not _save_and_block_module(blocked_name, orig_modules):
+ names_to_remove.append(blocked_name)
+ fresh_module = importlib.import_module(name)
finally:
- for blocked, module in orig_modules.items():
- sys.modules[blocked] = module
- return py_module
+ for orig_name, module in orig_modules.items():
+ sys.modules[orig_name] = module
+ for name_to_remove in names_to_remove:
+ del sys.modules[name_to_remove]
+ return fresh_module
def get_attribute(obj, name):
diff --git a/Lib/test/test_warnings.py b/Lib/test/test_warnings.py
index 4c3b43a..9764783 100644
--- a/Lib/test/test_warnings.py
+++ b/Lib/test/test_warnings.py
@@ -10,8 +10,8 @@
import warnings as original_warnings
-py_warnings = test_support.import_fresh_module('warnings', ['_warnings'])
-c_warnings = test_support.import_fresh_module('warnings')
+py_warnings = test_support.import_fresh_module('warnings', blocked=['_warnings'])
+c_warnings = test_support.import_fresh_module('warnings', fresh=['_warnings'])
@contextmanager
def warnings_state(module):