@Test
  public void testSetBothSuccess() {
    when(primarySource.set(any())).thenReturn(true);
    when(secondarySource.set(any())).thenReturn(true);
    DataNodeConfig config = createConfig(1, 1);
    assertTrue("Expected success response", compositeSource.set(config));
    verify(primarySource).set(config);
    verify(secondarySource).set(config);
  }
Test composite set with both sources returning the same result.
ambry-clustermap/src/test/java/com/github/ambry/clustermap/CompositeDataNodeConfigSourceTest.java