Add tests for multiprocessing forkserver and dependencies

* **Lib/test/test_multiprocessing_forkserver.py**
  - Add tests for shared memory access, process return code, and signal handling in forkserver.

* **Lib/test/test_dependencies.py**
  - Add tests to check for the existence of `pyvenv.cfg` and availability of `multiprocessing.shared_memory`, `ssl`, `pdb`, and `warnings` modules.

Lib/test/test_dependencies.py

@@ -0,0 +1,36 @@
+import unittest
+import os
+import sys
+
+class TestDependencies(unittest.TestCase):
+
+    def test_pyvenv_cfg_exists(self):
+        venv_path = os.path.join(sys.prefix, 'pyvenv.cfg')
+        self.assertTrue(os.path.exists(venv_path), f"{venv_path} does not exist")
+
+    def test_shared_memory_access(self):
+        try:
+            import multiprocessing.shared_memory
+        except ImportError:
+            self.fail("multiprocessing.shared_memory module is not available")
+
+    def test_ssl_module(self):
+        try:
+            import ssl
+        except ImportError:
+            self.fail("ssl module is not available")
+
+    def test_pdb_module(self):
+        try:
+            import pdb
+        except ImportError:
+            self.fail("pdb module is not available")
+
+    def test_warnings_module(self):
+        try:
+            import warnings
+        except ImportError:
+            self.fail("warnings module is not available")
+
+if __name__ == '__main__':
+    unittest.main()

Lib/test/test_multiprocessing_forkserver.py

@@ -0,0 +1,48 @@
+import unittest
+import multiprocessing
+import os
+import signal
+import time
+
+class TestForkserver(unittest.TestCase):
+
+    def setUp(self):
+        self.manager = multiprocessing.Manager()
+        self.shared_dict = self.manager.dict()
+
+    def tearDown(self):
+        self.manager.shutdown()
+
+    def test_shared_memory_access(self):
+        def worker(shared_dict):
+            shared_dict['key'] = 'value'
+
+        process = multiprocessing.Process(target=worker, args=(self.shared_dict,))
+        process.start()
+        process.join()
+
+        self.assertEqual(self.shared_dict['key'], 'value')
+
+    def test_forkserver_process_return_code(self):
+        def worker():
+            os._exit(1)
+
+        process = multiprocessing.Process(target=worker)
+        process.start()
+        process.join()
+
+        self.assertEqual(process.exitcode, 1)
+
+    def test_forkserver_signal_handling(self):
+        def worker():
+            time.sleep(5)
+
+        process = multiprocessing.Process(target=worker)
+        process.start()
+        os.kill(process.pid, signal.SIGTERM)
+        process.join()
+
+        self.assertEqual(process.exitcode, -signal.SIGTERM)
+
+if __name__ == '__main__':
+    unittest.main()