test: Fix error message validation in test_puredispatch.py. (#891)

Corrected the usage of `assertRaises` in `test_puredispatch.py`.
Previously, `msg` was mistakenly used as error
message validation.
This has been updated to use `assertRaisesRegex`
with a compiled regex pattern to ensure proper
validation of the expected `ValueError` messages.

Author: junkmd

comtypes/test/test_puredispatch.py

@@ -1,3 +1,4 @@
+import re
 import unittest as ut
 import winreg
 
@@ -12,6 +13,8 @@
 HKCR = 0  # HKEY_CLASSES_ROOT
 HKCU = 1  # HKEY_CURRENT_USER
 
+NAMED_PARAM_ERRMSG = "named parameters not yet implemented"
+
 
 class Test_Installer(ut.TestCase):
     def test_registry_value_with_root_key_value(self):
@@ -58,20 +61,20 @@ def test_registry_value_with_named_params(self):
         # if named arguments are passed to prevent invalid calls.
         # TODO: After named parameters are supported, this will become a test to
         # assert the return value.
-        ERRMSG = "named parameters not yet implemented"
-        with self.assertRaises(ValueError, msg=ERRMSG):
+        PTN = re.compile(rf"^{re.escape(NAMED_PARAM_ERRMSG)}$")
+        with self.assertRaisesRegex(ValueError, PTN):
             inst.RegistryValue(Root=HKCR, Key=".txt", Value="")  # type: ignore
-        with self.assertRaises(ValueError, msg=ERRMSG):
+        with self.assertRaisesRegex(ValueError, PTN):
             inst.RegistryValue(Value="", Root=HKCR, Key=".txt")  # type: ignore
-        with self.assertRaises(ValueError, msg=ERRMSG):
+        with self.assertRaisesRegex(ValueError, PTN):
             inst.RegistryValue(HKCR, Key=".txt", Value="")  # type: ignore
-        with self.assertRaises(ValueError, msg=ERRMSG):
+        with self.assertRaisesRegex(ValueError, PTN):
             inst.RegistryValue(HKCR, ".txt", Value="")  # type: ignore
-        with self.assertRaises(ValueError, msg=ERRMSG):
+        with self.assertRaisesRegex(ValueError, PTN):
             inst.RegistryValue(Root=HKCU, Key=r"Control Panel\Desktop")  # type: ignore
-        with self.assertRaises(ValueError, msg=ERRMSG):
+        with self.assertRaisesRegex(ValueError, PTN):
             inst.RegistryValue(Key=r"Control Panel\Desktop", Root=HKCR)  # type: ignore
-        with self.assertRaises(ValueError, msg=ERRMSG):
+        with self.assertRaisesRegex(ValueError, PTN):
             inst.RegistryValue(HKCR, Key=r"Control Panel\Desktop")  # type: ignore
 
     def test_product_state(self):