require("should");

describe("functional programming", function(){
    it("map an array of numbers", function(){
        var numbers = [1, 2, 3, 4];
        var doubles = numbers.map(function(i){
            return i*2;
        });

        doubles.should.be.eql([2, 4, 6, 8]);
    });

    it("use map reverse a string", function(){
        var str='12345';
        var r = [].map.call(str, function(x){
            return x;
        }).reverse().join('');

        r.should.be.eql('54321');
    });

    it("filter out small values", function(){
        var filtered = [1,2,3,4,5].filter(function(x){
            return x > 3;
        });

        filtered.should.be.eql([4,5]);
    });

    it("sum up all values within an array", function(){
        var total = [1,2,3,4].reduce(function(a, b){
            return a+b;
        }, 3); //3 is a initial value

        total.should.be.eql(13);
    });

    it("return a portion of an existing array", function(){
        var fruits = ['Banana','Orange','Lemon','Apple','Mango'].slice(1, 3) // [1, 3)

        fruits.should.be.eql(['Orange', 'Lemon']);
    });

    it("insert a element at index 2", function(){
        var myFish = ['angel', 'clown', 'mandarin', 'surgeon'];
        var removed = myFish.splice(2, 0, 'drum');

        myFish.should.be.eql(['angel', 'clown', 'drum','mandarin', 'surgeon']);
        removed.should.be.eql([]);
    });

    it("remove a element at index 3", function(){
        var myFish = ['angel', 'clown', 'mandarin', 'surgeon'];
        var removed = myFish.splice(3, 1);

        myFish.should.be.eql(['angel', 'clown', 'mandarin']);
        removed.should.be.eql(['surgeon']);
    });

    it("insert 1 element from index 2 and insert an element", function(){
        var myFish = ['angel', 'clown', 'mandarin', 'surgeon'];
        var removed = myFish.splice(2, 1, "trumpet");

        myFish.should.be.eql(['angel', 'clown', 'trumpet', 'surgeon']);
        removed.should.be.eql(['mandarin']);
    });
});