Add support for alternate keychains in expression.

CHANGES.rst

@@ -2,6 +2,8 @@ v23.6.0
 -------
 
 * #575: Only require ``importlib_metadata`` on older Pythons.
+* #579: Add ``.with_keychain`` method on macOS for easy reference
+  to alternate keychains.
 
 v23.5.1
 -------

keyring/backends/macOS/__init__.py

@@ -66,3 +66,8 @@ def delete_password(self, service, username):
             raise PasswordDeleteError(
                 "Can't delete password in keychain: " "{}".format(e)
             )
+
+    def with_keychain(self, keychain):
+        alt = Keyring()
+        alt.keychain = keychain
+        return alt

tests/backends/test_macOS.py

@@ -12,3 +12,8 @@
 class Test_macOSKeychain(BackendBasicTests):
     def init_keyring(self):
         return macOS.Keyring()
+
+    def test_alternate_keychain(self):
+        alt = self.keyring.with_keychain('abcd')
+        assert alt.keychain == 'abcd'
+        assert self.keyring.keychain != 'abcd'