比较两个XML字符串，忽略元素顺序

Question

假设我有两个xml字符串

<test>
  <elem>a</elem>
  <elem>b</elem>
</test>

<test>
  <elem>b</elem>
  <elem>a</elem>
</test>

如何编写一个比较这两个字符串并忽略元素顺序的测试？

我希望测试尽可能短，没有10行XML解析等的位置。我正在寻找一个简单的断言或类似内容。

我有这个（不起作用）

   Diff diff = XMLUnit.compareXML(expectedString, actualString);   
   XMLAssert.assertXMLEqual("meh", diff, true);

Answer 1

我原来的答案已经过时了。如果必须再次构建它，我将使用xmlunit 2和xmlunit-
matchers。请注意，对于xml单元，不同的顺序始终是“相似”而不是相等。

@Test
public void testXmlUnit() {
    String myControlXML = "<test><elem>a</elem><elem>b</elem></test>";
    String expected = "<test><elem>b</elem><elem>a</elem></test>";
    assertThat(myControlXML, isSimilarTo(expected)
            .withNodeMatcher(new DefaultNodeMatcher(ElementSelectors.byNameAndText)));
    //In case you wan't to ignore whitespaces add ignoreWhitespace().normalizeWhitespace()
    assertThat(myControlXML, isSimilarTo(expected)
        .ignoreWhitespace()
        .normalizeWhitespace()
        .withNodeMatcher(new DefaultNodeMatcher(ElementSelectors.byNameAndText)));
}

如果有人仍然不想使用纯Java实现，那就是。此实现从xml中提取内容，并比较列表的忽略顺序。

public static Document loadXMLFromString(String xml) throws Exception {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    InputSource is = new InputSource(new StringReader(xml));
    return builder.parse(is);
}

@Test
public void test() throws Exception {
    Document doc = loadXMLFromString("<test>\n" +
            "  <elem>b</elem>\n" +
            "  <elem>a</elem>\n" +
            "</test>");
    XPathFactory xPathfactory = XPathFactory.newInstance();
    XPath xpath = xPathfactory.newXPath();
    XPathExpression expr = xpath.compile("//test//elem");
    NodeList all = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
    List<String> values = new ArrayList<>();
    if (all != null && all.getLength() > 0) {
        for (int i = 0; i < all.getLength(); i++) {
            values.add(all.item(i).getTextContent());
        }
    }
    Set<String> expected = new HashSet<>(Arrays.asList("a", "b"));
    assertThat("List equality without order",
            values, containsInAnyOrder(expected.toArray()));
}