Conception and APIs of Sinon.JS

[switer]

Sinon is a testing suite.

Spy

A test spy is a function that records arguments, return value, the value of this and exception thrown (if any) for all its calls.

sample

"test should call subscribers with message as first argument" : function () {
    var message = 'an example message';
    var spy = sinon.spy();

    PubSub.subscribe(message, spy);
    PubSub.publishSync(message, "some payload");

    assert(spy.calledWith(message));
}

Stub

Test stubs are functions (spies) with pre-programmed behavior. They support the full test spy API in addition to methods which can be used to alter the stub’s behavior.

As spies, stubs can be either anonymous, or wrap existing functions. When wrapping an existing function with a stub, the original function is not called.

sample

"test should call all subscribers, even if there are exceptions" : function(){
    var message = 'an example message';
    var error = 'an example error message';
    var stub = sinon.stub().throws();
    var spy1 = sinon.spy();
    var spy2 = sinon.spy();

    PubSub.subscribe(message, stub);
    PubSub.subscribe(message, spy1);
    PubSub.subscribe(message, spy2);

    PubSub.publishSync(message, undefined);

    assert(spy1.called);
    assert(spy2.called);
    assert(stub.calledBefore(spy1));
}

Mock

Mocks (and mock expectations) are fake methods (like spies) with pre-programmed behavior (like stubs) as well as pre-programmed expectations. A mock will fail your test if it is not used as expected.

sample

"test should call all subscribers when exceptions": function () {
    var myAPI = { method: function () {} };

    var spy = sinon.spy();
    var mock = sinon.mock(myAPI);
    mock.expects("method").once().throws();

    PubSub.subscribe("message", myAPI.method);
    PubSub.subscribe("message", spy);
    PubSub.publishSync("message", undefined);

    mock.verify();
    assert(spy.calledOnce);
}