Testing a mixin function
Your code is correct, but can be simplified. ok method usually gets an expression rather than a in-place function that is immediately evaluated.

Here is how I would write this test:

test('Mixin Test Runner', function () {
    var receiver = {
        name: 'Abul Moksud',
        age: '60'
    };

    var supplier = {
        hands: 2
    };

    mixin(receiver, supplier);

    //Assertion phase
    ok(receiver.hasOwnProperty("hands"), "hands property is defined on reciever");
    equal(receiver.hands, 2, "Abul Moksud now has two hands");
});