pythongh-108388: regrtest splits test_asyncio package

Currently, test_asyncio package is only splitted into sub-tests when
using command "./python -m test". With this change, it's also
splitted when passing it on the command line:
"./python -m test test_asyncio".

Author: vstinner

Lib/test/libregrtest/main.py

@@ -11,7 +11,7 @@
 import unittest
 from test.libregrtest.cmdline import _parse_args
 from test.libregrtest.runtest import (
-    findtests, runtest, get_abs_module, is_failed,
+    findtests, split_test_packages, runtest, get_abs_module, is_failed,
     STDTESTS, NOTTESTS, PROGRESS_MIN_TIME,
     Passed, Failed, EnvChanged, Skipped, ResourceDenied, Interrupted,
     ChildError, DidNotRun)
@@ -263,7 +263,11 @@ def find_tests(self, tests):
             alltests = findtests(self.ns.testdir, stdtests, nottests)
 
         if not self.ns.fromfile:
-            self.selected = self.tests or self.ns.args or alltests
+            self.selected = self.tests or self.ns.args
+            if self.selected:
+                self.selected = split_test_packages(self.selected)
+            else:
+                self.selected = alltests
         else:
             self.selected = self.tests
         if self.ns.single:

Lib/test/libregrtest/runtest.py

@@ -178,12 +178,24 @@ def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS, *, split_test_
             if mod in split_test_dirs:
                 subdir = os.path.join(testdir, mod)
                 mod = f"{base_mod or 'test'}.{mod}"
-                tests.extend(findtests(subdir, [], nottests, split_test_dirs=split_test_dirs, base_mod=mod))
+                tests.extend(findtests(subdir, [], nottests, split_test_dirs=(), base_mod=mod))
             elif ext in (".py", ""):
                 tests.append(f"{base_mod}.{mod}" if base_mod else mod)
     return stdtests + sorted(tests)
 
 
+def split_test_packages(tests):
+    testdir = findtestdir()
+    splitted = []
+    for name in tests:
+        if name in SPLITTESTDIRS:
+            subdir = os.path.join(testdir, name)
+            splitted.extend(findtests(subdir, [], NOTTESTS, split_test_dirs=(), base_mod=name))
+        else:
+            splitted.append(name)
+    return splitted
+
+
 def get_abs_module(ns: Namespace, test_name: str) -> str:
     if test_name.startswith('test.') or ns.testdir:
         return test_name