// Then
        assertNull(retrievedDigest);
        verify(messageBlock).setDigest(null);
    }

    @Test
    @DisplayName("Test setResponse and getResponse methods")
    void testSetAndGetResponse() {
        // Given
        doNothing().when(messageBlock).setResponse(response);
        when(messageBlock.getResponse()).thenReturn(response);

        // When
        messageBlock.setResponse(response);