gerich-home/it-depends

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

describe('general change callback', function () {
    var calls;
    var observableValue;
    var subscription;
    
    var expectLastChanges = function(expected) {
        expect(calls.lastChange.changed).to.equal(expected.changed);
        expect(calls.lastChange.from).to.equal(expected.from);
        expect(calls.lastChange.to).to.equal(expected.to);
    };


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

        observableValue = itDepends.value('Bob');

        subscription = itDepends.onChange(function(changed, from, to) {
            callsSpy.count++;
            callsSpy.lastChange = { changed: changed, from: from, to: to };
        });
    });
    
    afterEach(function() {
        subscription.disable();
    });
    
    it('should not be triggered when new subscription is created', function () {
        expect(calls.count).to.equal(0);
    });

    it('should not be triggered when observable is not changed', function () {
        observableValue.write('Bob');
        expect(calls.count).to.equal(0);
    });
    
    context('when observable is changed', function() {
        beforeEach(function() {
            observableValue.write('Jack');
        });

        it('should be triggered once', function () {
            expect(calls.count).to.equal(1);
            expectLastChanges({ changed: observableValue, from: 'Bob', to: 'Jack' });
        });

        it('should be triggered once when changed back', function () {
            observableValue.write('Bob');
            expect(calls.count).to.equal(2);
            expectLastChanges({ changed: observableValue, from: 'Jack', to: 'Bob' });
        });
    });
    
    context('when other observable value is created', function() {
        var otherValue;
        
        beforeEach(function() {
            otherValue = itDepends.value('Jack');
        });
        
        it('should not be triggered when other observable is created', function () {
            expect(calls.count).to.equal(0);
        });
    
        it('should be triggered once when observable is changed', function () {
            observableValue.write('Jack');
            
            expect(calls.count).to.equal(1);
            expectLastChanges({ changed: observableValue, from: 'Bob', to: 'Jack' });
        });
    
        it('should be triggered once when other observable is changed', function () {
            otherValue.write('James');
            
            expect(calls.count).to.equal(1);
            expectLastChanges({ changed: otherValue, from: 'Jack', to: 'James' });
        });
    });
    
    context('when there is a computed depending on observable value', function() {
        var computedValue;
        
        beforeEach(function() {
            computedValue = itDepends.computed(function() {
                return "Hello, " + observableValue();
            });
        });
    
        it('should be triggered once when observable is changed', function () {
            observableValue.write('Jack');
            
            expect(calls.count).to.equal(1);
            expectLastChanges({ changed: observableValue, from: 'Bob', to: 'Jack' });
        });
    });
    
    context('when disabled', function() {
        beforeEach(function() {
            subscription.disable();
        });
    
        it('should not be triggered when observable is changed', function () {
            observableValue.write('Jack');
            
            expect(calls.count).to.equal(0);
        });

        context('when enabled back', function() {
            beforeEach(function() {
                subscription.enable();
            });
        
            it('should be triggered when observable is changed', function () {
                observableValue.write('Jack');
                
                expect(calls.count).to.equal(1);
                expectLastChanges({ changed: observableValue, from: 'Bob', to: 'Jack' });
            });
        });
    });
});