Fix ChainerBackend.delete_password to try all backends

keyring/backends/chainer.py

@@ -5,6 +5,7 @@
 
 from .. import backend
 from ..compat import properties
+from ..errors import PasswordDeleteError
 from . import fail
 
 
@@ -63,6 +64,9 @@ def delete_password(self, service, username):
                 return keyring.delete_password(service, username)
             except NotImplementedError:
                 pass
+            except PasswordDeleteError:
+                if keyring == self.backends[-1]:
+                    raise
 
     def get_credential(self, service, username):
         for keyring in self.backends:

tests/backends/test_chainer.py

@@ -2,6 +2,7 @@
 
 import keyring.backends.chainer
 from keyring import backend
+from keyring.errors import PasswordDeleteError
 
 
 @pytest.fixture
@@ -30,6 +31,51 @@ def set_password(self, system, user, password):
     monkeypatch.setattr('keyring.backend.get_all_keyring', get_two)
 
 
+@pytest.fixture
+def delete_test_keyrings(monkeypatch):
+    """
+    Fixture that creates backends where passwords exist in lower priority backend.
+    """
+
+    class HighPriorityKeyring(backend.KeyringBackend):
+        priority = 2
+
+        def get_password(self, system, user):
+            return None
+
+        def set_password(self, system, user, password):
+            pass
+
+        def delete_password(self, system, user):
+            raise PasswordDeleteError("Password not found")
+
+    class LowPriorityKeyring(backend.KeyringBackend):
+        priority = 1
+        storage = {}
+
+        def __init__(self):
+            self.storage = {('test', 'user'): 'old-password'}
+
+        def get_password(self, system, user):
+            return self.storage.get((system, user))
+
+        def set_password(self, system, user, password):
+            pass
+
+        def delete_password(self, system, user):
+            key = (system, user)
+            if key in self.storage:
+                del self.storage[key]
+            else:
+                raise PasswordDeleteError("Password not found")
+
+    high = HighPriorityKeyring()
+    low = LowPriorityKeyring()
+
+    monkeypatch.setattr('keyring.backend.get_all_keyring', lambda: [high, low])
+    return high, low
+
+
 class TestChainer:
     def test_chainer_gets_from_highest_priority(self, two_keyrings):
         chainer = keyring.backends.chainer.ChainerBackend()
@@ -45,3 +91,41 @@ def test_chainer_defers_to_fail(self, monkeypatch):
         assert keyring.backend.by_priority(
             keyring.backends.chainer.ChainerBackend
         ) < keyring.backend.by_priority(keyring.backends.fail.Keyring)
+
+    def test_delete_password_tries_all_backends(self, delete_test_keyrings):
+        """
+        Test that delete_password tries all backends in the chain,
+        not just the highest priority one. Addresses issue #697.
+        """
+        high, low = delete_test_keyrings
+        chainer = keyring.backends.chainer.ChainerBackend()
+
+        # Verify set_password is defined (required by ABC) but is a no-op
+        high.set_password('test', 'user', 'ignored')
+        low.set_password('test', 'extra', 'ignored')
+
+        # Verify the password exists in the low priority backend
+        assert low.get_password('test', 'user') == 'old-password'
+        # Verify it doesn't exist in high priority backend
+        assert high.get_password('test', 'user') is None
+        # Verify chainer can retrieve it
+        assert chainer.get_password('test', 'user') == 'old-password'
+
+        # Now delete it via chainer - should succeed even though high priority backend fails
+        chainer.delete_password('test', 'user')
+
+        # Verify it's deleted from low priority backend
+        assert low.get_password('test', 'user') is None
+        # Verify chainer can't retrieve it anymore
+        assert chainer.get_password('test', 'user') is None
+
+    def test_delete_password_raises_if_all_backends_fail(self, delete_test_keyrings):
+        """
+        Test that delete_password raises PasswordDeleteError if all backends fail.
+        """
+        high, low = delete_test_keyrings
+        chainer = keyring.backends.chainer.ChainerBackend()
+
+        # Try to delete a password that doesn't exist anywhere
+        with pytest.raises(PasswordDeleteError):
+            chainer.delete_password('nonexistent', 'user')