sinon@next: sinon.replace only works on own property

[mantoni]

While playing with #1586, I noticed that sinon.replace(obj, 'prop', fake) only works if 'prop' is an own property of obj. I can only make this work with sinon.replace(Object.getPrototypeOf(obj), 'prop', fake).

sinon.replace should allow to replace properties up the prototype chain, like sandbox.stub does.

[mroderick]

I tried adding a test to reproduce your scenario

it("should replace property on prototype", function () {
    var Person = function (name) {
        this.name = name;
    };
    var Customer = function (name) {
        Person.call(this, name);
    };

    Customer.prototype = Object.create(Person.prototype);
    Customer.prototype.constructor = Customer;

    var customer = new Customer("Some Name");
    var replacement = "Some Other Name";

    this.sandbox.replace(customer, "name", replacement);

    assert.equals(customer.name, replacement);
});

However, this passes with no changes to sandbox.js.

I don't think I understood your description correctly. Can you suggest an improvement to the test, that would make it clear what replace is currently not capable of?

[mantoni]

@mroderick The reason your example doesn't fail is because this.name = name creates an own property of the object. If you'd add a method to the Person prototype and try to replace it, that would fail. You don't need the derived Customer.

Anyway, I've created #1704 to illustrate the issue with a failing test.

[mroderick]

Fixed with #1705