The following example shows how to invoke a mock asynchronous callout in a test for a Web service call that uses HTTPRequest. To simulate callouts in continuations, call these methods of the Test class: setContinuationResponse(requestLabel, mockResponse) and invokeContinuationMethod(controller, request).
The controller class to test is listed first, followed by the test class. The controller class from Make Long-Running Callouts from a Visualforce Page is reused here.
public with sharing class ContinuationController { // Unique label corresponding to the continuation request public String requestLabel; // Result of callout public String result {get;set;} // Endpoint of long-running service private static final String LONG_RUNNING_SERVICE_URL = '<Insert your service URL>'; // Action method public Object startRequest() { // Create continuation with a timeout Continuation con = new Continuation(40); // Set callback method con.continuationMethod='processResponse'; // Create callout request HttpRequest req = new HttpRequest(); req.setMethod('GET'); req.setEndpoint(LONG_RUNNING_SERVICE_URL); // Add callout request to continuation this.requestLabel = con.addHttpRequest(req); // Return the continuation return con; } // Callback method public Object processResponse() { // Get the response by using the unique label HttpResponse response = Continuation.getResponse(this.requestLabel); // Set the result variable that is displayed on the Visualforce page this.result = response.getBody(); // Return null to re-render the original Visualforce page return null; } }
This example shows the test class corresponding to the controller. This test class contains a test method for testing an asynchronous callout. In the test method, Test.setContinuationResponse sets a mock response, and Test.invokeContinuationMethod causes the callback method for the continuation to be executed. The test ensures that the callback method processed the mock response by verifying that the controller’s result variable is set to the expected response.
@isTest public class ContinuationTestingForHttpRequest { public static testmethod void testWebService() { ContinuationController controller = new ContinuationController(); // Invoke the continuation by calling the action method Continuation conti = (Continuation)controller.startRequest(); // Verify that the continuation has the proper requests Map<String, HttpRequest> requests = conti.getRequests(); system.assert(requests.size() == 1); system.assert(requests.get(controller.requestLabel) != null); // Perform mock callout // (i.e. skip the callout and call the callback method) HttpResponse response = new HttpResponse(); response.setBody('Mock response body'); // Set the fake response for the continuation Test.setContinuationResponse(controller.requestLabel, response); // Invoke callback method Object result = Test.invokeContinuationMethod(controller, conti); // result is the return value of the callback System.assertEquals(null, result); // Verify that the controller's result variable // is set to the mock response. System.assertEquals('Mock response body', controller.result); } }