@Test
public void getExtras_shouldReturnCopyOfExtrasMapFromBaseNativeAd() {

    final Map<String, Object> extras = subject.getExtras();
    assertThat(extras.size()).isEqualTo(2);
    assertThat(extras.get("extra")).isEqualTo("extraValue");
    assertThat(extras.get("extraImage")).isEqualTo("extraImageUrl");
    assertThat(extras).isNotSameAs(mNativeAd.getExtras());
}