@Test
public void testMergeNodes() throws Exception {

    List<Node> fromParents = new ArrayList<>();
    fromParents.add(ManifestTestUtils.createNode(
            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                    "                        <sentinel3:duration>179</sentinel3:duration>").getFirstChild());
    fromParents.add(ManifestTestUtils.createNode(
            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                    "                     <sentinel3:duration>179</sentinel3:duration>").getFirstChild());
    fromParents.add(ManifestTestUtils.createNode(
            "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
                    "                     <sentinel3:duration>179</sentinel3:duration>").getFirstChild());
    Document manifest = ManifestTestUtils.createDocument();
    final Element manifestElement = manifest.createElement("sentinel3:duration");
    manifest.appendChild(manifestElement);
    new DurationMerger().mergeNodes(fromParents, manifestElement, manifest);
    assertEquals(0, manifestElement.getAttributes().getLength());
    assertEquals(1, manifestElement.getChildNodes().getLength());
    assertEquals("537", manifestElement.getFirstChild().getNodeValue());
    assertEquals("537", manifestElement.getTextContent());
}