@Test
public void testAddAsset() throws Exception {

    Asset asset1 = new Asset();
    asset1.setUrl("aaaa");
    Asset asset2 = new Asset();
    asset2.setUrl("bbb");
    Asset asset3 = new Asset();
    asset3.setUrl("bbb");
    AssetGroup assetGroup = new AssetGroup();
    assetGroup.addAsset(asset1);
    assetGroup.addAsset(asset2);
    assetGroup.addAsset(asset3);
    assertEquals(2, assetGroup.getAssets().size());
    assertEquals(asset1, assetGroup.getAssets().get(0));
    assertEquals(asset2, assetGroup.getAssets().get(1));
}