@Test
public void testToString() {

    assertThat(newSample().toString())
            .isEqualTo(newSample().toString())
            .isEqualTo(new DataSource(PNAME, VERSION, ImmutableSortedMap.of(K3, V3, K2, V2, K1, V1)).toString())
            .isNotEqualTo(ZERO.toString());
}