尽管xPath似乎断言，Java XMLAssert仍然失败

Question

与org.custommonkey.xmlunit.XMLAssert存在严重问题，我在一个Doc中断言，其中包含以下xml。

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<soap:Fault>
<faultcode>soap:Client</faultcode>
<faultstring>Unmarshalling Error: cvc-maxLength-valid: Value 'WFWAFBA' with length = '7' is not facet-valid with respect to maxLength '3' for type 'ValidCode'. </faultstring>
</soap:Fault>
</soap:Body>
</soap:Envelope>

我正在使用以下xmlAssert

XMLAssert.assertXpathExists("//soap:Fault[faultcode='soap:Client']", doc);

我通过外部xPath检查器运行它，它找到了元素。有人能帮忙吗？

非常感谢！

编辑：命名空间设置为

  HashMap<String, String> m = new HashMap<String, String>();
  m.put("soap", "http://schemas.xmlsoap.org/soap/envelope/");
  NamespaceContext ctx = new SimpleNamespaceContext(m);
  XpathEngine engine = XMLUnit.newXpathEngine();
  engine.setNamespaceContext(ctx);