gerich-home/it-depends

var expect = require('chai').expect;
var itDepends = require('../out/build/it-depends.js');

describe('computed unrelated to other computed and value', function () {
    var calls;
    var unrelatedValue;
    var unrelatedComputed;
    var computedValue;

    beforeEach(function() {
        var counter = { count: 0 };
        calls = counter;

        unrelatedValue = itDepends.value('Bob');
        unrelatedComputed = itDepends.computed(function(){
            return 'Hello, ' + unrelatedValue();
        });

        computedValue = itDepends.computed(function(){
            counter.count++;
            return 'Hello';
        });
    });

    it('should not calculate when created', function () {
        expect(calls.count).to.equal(0);
    });

    it('should not calculate when other computed is calculated', function () {
        unrelatedComputed();
        expect(calls.count).to.equal(0);
    });

    it('should not calculate when other computed value changes', function () {
        unrelatedValue.write('Jack');
        unrelatedComputed();
        expect(calls.count).to.equal(0);
    });

    it('should calculate when requested', function () {
        var actualValue = computedValue();
        expect(actualValue).to.equal('Hello');
        expect(calls.count).to.equal(1);
    });
    
    context('when was calculated once', function () {
        beforeEach(function(){
            computedValue();
        });

        it('should not calculate when other computed is calculated', function () {
            unrelatedComputed();
            expect(calls.count).to.equal(1);
        });

        it('should not calculate when other computed value changes', function () {
            unrelatedValue.write('Jack');
            unrelatedComputed();
            expect(calls.count).to.equal(1);
        });

        it('should not calculate second time', function () {
            var actualValue = computedValue();
            expect(actualValue).to.equal('Hello');
            expect(calls.count).to.equal(1);
        });
    });
});