@Test
public void mergeNodes() throws Exception {

    List<Node> fromParents = new ArrayList<>();
    fromParents.add(ManifestTestUtils.createNode(
            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                    "            <sentinel3:productSize>2879317399</sentinel3:productSize>\n"));
    fromParents.add(ManifestTestUtils.createNode(
            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                    "            <sentinel3:productSize>2879317399</sentinel3:productSize>\n"));
    fromParents.add(ManifestTestUtils.createNode(
            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                    "            <sentinel3:productSize>2879317399</sentinel3:productSize>\n"));
    Document manifest = ManifestTestUtils.createDocument();
    final Element manifestElement = manifest.createElement("sentinel3:productSize");
    manifest.appendChild(manifestElement);
    new ProductSizeMerger(545765).mergeNodes(fromParents, manifestElement, manifest);
    assertEquals(0, manifestElement.getAttributes().getLength());
    assertEquals(1, manifestElement.getChildNodes().getLength());
    assertEquals("545765", manifestElement.getFirstChild().getNodeValue());
}