TDD and DOM Manipulation: The Chat Client - Test-Driven JavaScript Development - page 397

Listing 15.12 Recording this in stubFn
function stubFn(returnValue) {
var fn = function () {
fn.called = true;
fn.args = arguments;
fn.thisValue = this;
return returnValue;
};
fn.called = false;
return fn;
}
The next test, seen in Listing 15.13, uses the improved stubFn to assert that
the event handler is the controller's handleSubmit method, readily bound to the
controller object.
Listing 15.13 Expecting the event handler to be handleSubmit bound
to controller
"test should handle event with bound handleSubmit":
function () {
var stub = this.controller.handleSubmit = stubFn();
this.controller.setView(this.element);
dom.addEventHandler.args[2]();
assert(stub.called);
assertSame(this.controller, stub.thisValue);
}
This test shows another reason for not elevating the setView call to the setUp
method; here we need additional setup before calling it, to be sure the method
uses the stubbed handleSubmit method—not the original one, which would
fail our test indefinitely. Listing 15.14 updates the call to pass the test. Note that
the implementation requires the bind implementation from Chapter 6, Applied
Functions and Closures, in lib/function.js .