[Python-checkins] bpo-40275: Avoid importing asyncio in test.support (GH-19600)
Serhiy Storchaka
webhook-mailer at python.org
Sat Apr 25 03:04:15 EDT 2020
https://github.com/python/cpython/commit/3c8a5b459d68b4337776ada1e04f5b33f90a2275
commit: 3c8a5b459d68b4337776ada1e04f5b33f90a2275
branch: master
author: Serhiy Storchaka <storchaka at gmail.com>
committer: GitHub <noreply at github.com>
date: 2020-04-25T10:04:10+03:00
summary:
bpo-40275: Avoid importing asyncio in test.support (GH-19600)
* Import asyncio lazily in unittest (only when IsolatedAsyncioTestCase is used).
* Import asyncio.events lazily in test.support.
files:
A Misc/NEWS.d/next/Library/2020-04-20-18-50-25.bpo-40275.Ofk6J8.rst
M Lib/test/support/__init__.py
M Lib/unittest/__init__.py
diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index f3868c1041542..2b3a4147246ee 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -3,7 +3,6 @@
if __name__ != 'test.support':
raise ImportError('support must be imported from the test package')
-import asyncio.events
import collections.abc
import contextlib
import errno
@@ -3260,6 +3259,7 @@ def __gt__(self, other):
def maybe_get_event_loop_policy():
"""Return the global event loop policy if one is set, else return None."""
+ import asyncio.events
return asyncio.events._event_loop_policy
# Helpers for testing hashing.
diff --git a/Lib/unittest/__init__.py b/Lib/unittest/__init__.py
index ace3a6fb1dd97..348dc471f4c3d 100644
--- a/Lib/unittest/__init__.py
+++ b/Lib/unittest/__init__.py
@@ -57,7 +57,6 @@ def testMultiply(self):
__unittest = True
from .result import TestResult
-from .async_case import IsolatedAsyncioTestCase
from .case import (addModuleCleanup, TestCase, FunctionTestCase, SkipTest, skip,
skipIf, skipUnless, expectedFailure)
from .suite import BaseTestSuite, TestSuite
@@ -66,6 +65,7 @@ def testMultiply(self):
from .main import TestProgram, main
from .runner import TextTestRunner, TextTestResult
from .signals import installHandler, registerResult, removeResult, removeHandler
+# IsolatedAsyncioTestCase will be imported lazily.
# deprecated
_TextTestResult = TextTestResult
@@ -78,3 +78,18 @@ def load_tests(loader, tests, pattern):
# top level directory cached on loader instance
this_dir = os.path.dirname(__file__)
return loader.discover(start_dir=this_dir, pattern=pattern)
+
+
+# Lazy import of IsolatedAsyncioTestCase from .async_case
+# It imports asyncio, which is relatively heavy, but most tests
+# do not need it.
+
+def __dir__():
+ return globals().keys() | {'IsolatedAsyncioTestCase'}
+
+def __getattr__(name):
+ if name == 'IsolatedAsyncioTestCase':
+ global IsolatedAsyncioTestCase
+ from .async_case import IsolatedAsyncioTestCase
+ return IsolatedAsyncioTestCase
+ raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
diff --git a/Misc/NEWS.d/next/Library/2020-04-20-18-50-25.bpo-40275.Ofk6J8.rst b/Misc/NEWS.d/next/Library/2020-04-20-18-50-25.bpo-40275.Ofk6J8.rst
new file mode 100644
index 0000000000000..2093589f528b0
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-04-20-18-50-25.bpo-40275.Ofk6J8.rst
@@ -0,0 +1,2 @@
+The :mod:`asyncio` package is now imported lazily in :mod:`unittest` only
+when the :class:`~unittest.IsolatedAsyncioTestCase` class is used.
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