concreteImplementation.setLink(link);
            assertEquals(link, concreteImplementation.getLink());
        }

        @Test
        @DisplayName("Should get and set key")
        void testGetAndSetKey() {
            String key = "cache-key-123";

            // Test with mock
            when(mockReferralData.getKey()).thenReturn(key);
            doNothing().when(mockReferralData).setKey(key);