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MockIo library

MockIo is a simple library to help you test code that does calls by intercepting those calls and providing a server response of your own.

Files and namespaces

MockiIo is found in lib/lp/app/testing/mockio.js and its namespace is Y.lp.testing.mockio. The instrumentation helpers are in Y.lp.client because they need to be usable by production code.


Before you can test your code you need to instrument it to intercept calls. This is done by passing an extra argument to the function or adding an attribute to an objects config. By convention this parameter is called io_provider because it provides a replacement io method. During test you pass in an instance of MockIo via this parameter, in production you just leave it undefined (or pass in Y).

Here is an example for a class.

var MyClass = function(config) {
    this.io_provider = Y.lp.client.get_configured_io_provider(config);

MyClass.prototype.do_something() {

    // Some code that prepares an url and an io_config for an xhr request.

    // This is where used to be called., io_config);

Here is an example for a simple function.

var myfunc = function(param1, param2, io_provider) {

    // Some code that prepares an url and an io_config for an xhr request.

    // This is where used to be called.
    Y.lp.client.get_io_provider(io_provider).io(url, io_config);

Mocking io calls in tests

Mocking happens in three steps.

// 1. Create the MockIo instance.
var mock_io = new Y.lp.testing.mockio.MockIo();

// 2. Pass it to your instrumented code.
Y.mynamespace.myfunc(param1, param2, mock_io);

// 3. Prepare and send a response.
    responseText: "['Some JSON data']",
    responseHeaders: {'Content-type': 'application/json'}

// Now you can check what the succcess handler in your code did.

The success method is a convenience method that calls the respond method and sets status to 200 and statusText to OK. You can also call respond directly and pass in your own status and statusText. There is also a failure method which sends a status of 500 Internal server error. Obviously, the latter will result in the failure handler being called.

The above example responds to the last request that your code sent out. If your code sends out multiple requests, you have access to those through the requests attribute of MockIo which is a list of all received requests. You can respond to a request via its respond method.

var mock_io = Y.lp.testing.mockio.MockIo();

// This time myfunc will issue two requests.
Y.mynamespace.myfunc(param1, param2, mock_io);

// Check that the requests were received.
Y.Assert.areSame(2, mock_io.requests.length);

// Respond to each request in whatever way is appropriate.
    status: 200,
    responseText: "Some data"

    status: 404,
    statusText: "Not found"

You can explicitly access the last request via the last_request attribute.

Already instrumented code

The Launchpad client has already been instrumented. When you instantiate it, pass in a config with an io_provider attribute. As this usually happens in your code you will have to instrument it to receive the io_provider from your test harness.

An example is FormOverlay which now has an extra attribute io_provider which defaults to Y. In your test simply configure FormOverlay with an io_provider attribute and set that attribute to an instance of MockIo.

JavascriptUnitTesting/MockIo (last edited 2011-09-14 18:54:12 by nigelbabu)