} else {
            assertNull(renewed, "renew() may return null for failed renewal");
        }
    }

    @Test
    @DisplayName("Mockito: verify renew() interaction and return value")
    void mockitoInteraction(@Mock CredentialsInternal returned, @Mock SmbRenewableCredentials renewable) {
        // Arrange: stub renew() to return a mocked CredentialsInternal
        when(renewable.renew()).thenReturn(returned);

            assertArrayEquals(expected, ctx.initSecContext(src, off, len));
        }
    }

    @Nested
    @DisplayName("Mockito interactions")
    class MockitoInteractions {

        @Mock
        SSPContext mockCtx;

        // Helper exercising all SSPContext methods to verify call interactions.
        private void useContext(SSPContext ctx) throws Exception {