tests: Yield fake_save_manager from fixture

tests/helpers/fixtures.py

@@ -311,5 +311,5 @@ def fake_save_manager():
     """Create a mock of save-manager and register it into objreg."""
     fake_save_manager = unittest.mock.Mock(spec=savemanager.SaveManager)
     objreg.register('save-manager', fake_save_manager)
-    yield
+    yield fake_save_manager
     objreg.delete('save-manager')

tests/unit/browser/test_cookies.py

@@ -100,7 +100,7 @@ def test_cookie_jar_init(config_stub, fake_save_manager):
     """Test the CookieJar constructor."""
     line_parser_stub = [COOKIE1, COOKIE2]
     jar = cookies.CookieJar(line_parser=line_parser_stub)
-    assert objreg.get('save-manager').add_saveable.called
+    assert fake_save_manager.add_saveable.called
 
     # Test that cookies are added to the jar
     assert len(jar.allCookies()) == 2