[3.11] gh-108303: Add Lib/test/test_cppext/ sub-directory (#108325) (#108336)

gh-108303: Add Lib/test/test_cppext/ sub-directory (#108325)

* Move test_cppext to its own directory
* Rename setup_testcppext.py to setup.py
* Rename _testcppext.cpp to extension.cpp
* The source (extension.cpp) is now also copied by the test.

(cherry picked from commit 21dda09600)

Lib/test/test_cppext/__init__.py

@@ -10,9 +10,7 @@
 
 
 MS_WINDOWS = (sys.platform == 'win32')
-
-
-SETUP_TESTCPPEXT = support.findfile('setup_testcppext.py')
+SETUP = os.path.join(os.path.dirname(__file__), 'setup.py')
 
 
 @support.requires_subprocess()
@@ -74,14 +72,14 @@ def run_cmd(operation, cmd):
 
         # Build the C++ extension
         cmd = [python, '-X', 'dev',
-               SETUP_TESTCPPEXT, 'build_ext', '--verbose']
+               SETUP, 'build_ext', '--verbose']
         if std_cpp03:
             cmd.append('-std=c++03')
         run_cmd('Build', cmd)
 
         # Install the C++ extension
         cmd = [python, '-X', 'dev',
-               SETUP_TESTCPPEXT, 'install']
+               SETUP, 'install']
         run_cmd('Install', cmd)
 
         # Do a reference run. Until we test that running python

Lib/test/test_cppext/extension.cpp

@@ -1,5 +1,7 @@
 // gh-91321: Very basic C++ test extension to check that the Python C API is
 // compatible with C++ and does not emit C++ compiler warnings.
+//
+// The code is only built, not executed.
 
 // Always enable assertions
 #undef NDEBUG

Lib/test/test_cppext/setup.py

@@ -1,7 +1,7 @@
 # gh-91321: Build a basic C++ test extension to check that the Python C API is
 # compatible with C++ and does not emit C++ compiler warnings.
+import os.path
 import sys
-from test import support
 
 from setuptools import setup, Extension
 
@@ -9,7 +9,7 @@
 MS_WINDOWS = (sys.platform == 'win32')
 
 
-SOURCE = support.findfile('_testcppext.cpp')
+SOURCE = os.path.join(os.path.dirname(__file__), 'extension.cpp')
 if not MS_WINDOWS:
     # C++ compiler flags for GCC and clang
     CPPFLAGS = [

Makefile.pre.in

@@ -1959,6 +1959,7 @@ TESTSUBDIRS=	ctypes/test \
 		test/support \
 		test/test_asyncio \
 		test/test_capi \
+		test/test_cppext \
 		test/test_email \
 		test/test_email/data \
 		test/test_import \