MockHttpServletResponse : Checking xml content

I am testing a controller using MockMvc. This is what the response looks like:

MockHttpServletResponse:
              Status = 200
       Error message = null
             Headers = {Content-Type=[text/xml]}
        Content type = text/xml
                Body = <?xml version="1.0" encoding="UTF-8" standalone="yes"?><ns2:diagnosisCode xmlns:ns2="http://schemas.mycompany.co.za/health" effectiveStartDate="2014-03-05T00:00:00+02:00" effectiveEndDate="2014-03-05T23:59:59.999+02:00" diagnosisId="1"><diagnosisCodeId><codingSchemaCode>irrelevant schema</codingSchemaCode><diagnosisCode>irrelevant code</diagnosisCode></diagnosisCodeId></ns2:diagnosisCode>
       Forwarded URL = null
      Redirected URL = null
             Cookies = []

Pretty-printed version of the Body line:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns2:diagnosisCode xmlns:ns2="http://schemas.mycompany.co.za/health" effectiveStartDate="2014-03-05T00:00:00+02:00" effectiveEndDate="2014-03-05T23:59:59.999+02:00" diagnosisId="1">
    <diagnosisCodeId>
        <codingSchemaCode>irrelevant schema</codingSchemaCode>
        <diagnosisCode>irrelevant code</diagnosisCode>
    </diagnosisCodeId>
</ns2:diagnosisCode>

The call on MockMvc looks like

mockMvc.perform(
        get("/diagnostic/diagnosisCodes/{schema}/{code}", IRRELEVANT_SCHEMA, IRRELEVANT_CODE).accept(MediaType.TEXT_XML))
        .andDo(print())
        .andExpect(content().contentType(MediaType.TEXT_XML))
        .andExpect(status().isOk())
        .andExpect(xpath("diagnosisCodeId/diagnosisCode").string(IRRELEVANT_CODE))
        .andExpect(xpath("diagnosisCodeId/codingSchemaCode").string(IRRELEVANT_SCHEMA));

I am pretty sure I am misunderstanding how I'm supposed to use XPath here, but why is this assertion failing? What should my expectation look like?

java.lang.AssertionError: XPath diagnosisCode expected:<irrelevant code> but was:<>

Solution

I'm not totally sure what the XPath context is (or whether it is the document node), but I see two possible problems and guess both apply:

You try to match < diagnosisCodeId/> elements that are the root element. There are none, but they're children of <diagnosisCode>. Either include an axis step for the root node (probably better way) or use the descendant-or-self axis step // in front of the query.
```
/diagnosisCode/diagnosisCodeId/diagnosisCode
//diagnosisCodeId/diagnosisCode
```
The document uses namespaces (for the root element). In addition to the root element problem described above, either register that namespace (better solution, but I don't know how to do this in spring MVC) or ignore it using following workaround:
```
/*[local-name() = 'diagnosisCode']/diagnosisCodeId/diagnosisCode
```
Which first matches all child nodes, but then limits to the ones having the apropriate element name (ignoring namespaces).

By adding XPath 2.0 support (for example by including Saxon as library), you can also use the wildcard namespace matcher:
```
/*:diagnosisCode/diagnosisCodeId/diagnosisCode
```
If you register the namespace URI http://schemas.mycompany.co.za/health as ns2, the query would look like
```
/ns2:diagnosisCode/diagnosisCodeId/diagnosisCode
```