Java Functional Testing Http Callback - cucumber-java

Question

I'm using Cucumber to test my service when it is deployed to a container. The request contains a URL the service calls when the operation is successful. What is a good way to create a Cucumber test that waits for the Http callback? The Gherkin script would look something like.
Scenario: Process Order
Given An Order has been submitted
When the Order is processed
Then the order process service calls back with a successful status message
What would the Java glue code look like?

Answer 1

Here's the solution I came up with using an embedded http server. In the OrderSteps.java glue code I added a class used to start the server on another thread.
private static class Callback implements Runnable
{
public void run()
{
HttpServer server;
try
{
server = HttpServer.create(new InetSocketAddress(8000), 0);
server.createContext("/callback", new CallbackHandler());
server.setExecutor(null); // creates a default executor
server.start();
}
catch (IOException e)
{
logger.debug("HTTP server loop failure.", e);
}
}
static class CallbackHandler implements HttpHandler
{
#Override
public void handle(HttpExchange t) throws IOException
{
// Read the message and set the global variable
// which informs the main test thread a callback
// has been received.
InputStream is=t.getRequestBody();
byte[] buf=new byte[1000];
int len=is.read(buf);
OrderSteps.receivedCallback=new String(buf,0,len);
String response = "Callback received.";
t.sendResponseHeaders(200, response.length());
// Send response
OutputStream os = t.getResponseBody();
os.write(response.getBytes());
os.close();
}
}
}
Then in the OrderSteps class, in the step/method that publishes the Order, the server thread is started and then the order is submitted. This guarantees the server will receive the callback, since it is listening before the order is submitted.
// Start a listener for the callback.
Thread callbackThread = new Thread(new Callback());
callbackThread.start();
In the step/method that checks if the callback was received, there's a loop checking the static variable to see if it has been set.
// Allow 5 seconds for the callback to occur.
for (int i = 0; i < 5; i++)
{
if (receivedCallback != null) {
break;
}
Thread.sleep(1000);
}
if (receivedCallback == null) fail("Callback was not received.");
assertEquals("Expected callback message", receivedCallback);