Ajax testing - JUnit in Action - page 247

13.7 Testing services with HttpClient

The idea behind testing the application services layer separately is to validate each ser-
vice independently from HTML , JavaScript, and DOM and how the application uses
the data. An application calls a service from JavaScript through the XMLHttpRequest
object. Here, we use XMLHttpRequest to refer to the standard JavaScript XMLHttp-
Request object and to the Microsoft ActiveX XMLHTTP objects Microsoft.XMLHTTP
and Msxml2.XMLHTTP . Our goal is to emulate an XMLHttpRequest object by using
HTTP as the transport mechanism and XML and JSON as example data formats. We
use the Apache Commons HttpClient to provide HTTP support, Java's built-in XML
support, and jslint4java to check that JSON documents are well formed.

13.7.1 Calling an XML service

To simplify this example, we've made the chapter's example webapp directory an IIS
virtual directory so that we can run the unit tests from Ant locally. A production Ant
build would start and stop a web container like Jetty around the unit test invocations.
Our first XML service test in listing 13.10 makes sure that we're getting back from the
server the expected XML document. A second test validates the document.

Listing 13.10 An XML service test

@Test
public void testGetXmlBasicCheck() throws IOException {
HttpClient httpClient = new HttpClient();
GetMethod get = new GetMethod(
" http://localhost/ch13personal/personal.xml");
String responseString;
try {
httpClient.executeMethod(get);
InputStream input = get.getResponseBodyAsStream();
responseString = IOUtils.toString(input, "UTF-8");
} finally {
get.releaseConnection();
}
Assert.assertTrue(responseString, responseString.startsWith(
"<?xml version=\"1.0\" encoding=\"UTF-8\"?>"));
// more...
}
The test starts by creating an Apache Commons HttpClient b and defining the
HTTP GET method C with a URL for our XML document fixture. The URL specified in
the GetMethod constructor is application specific and must include parameters if
appropriate for a given test. The test then executes the HTTP GET method D and
reads the data back from the server. Note the use of the Apache Commons IO API
IOUtils.toString to read the response stream in a string as a one-liner E . The code
does this synchronously, unlike a standard Ajax application. We then guarantee that
HttpClient resources are freed by calling releaseConnection from a finally block
F . We can now check that the data from the server is as expected. For this first test, all

B

C

D

E

F

G