into.js

var R = require('../source/index.js');
var eq = require('./shared/eq.js');


describe('into', function() {
  var add = R.add;
  var isOdd = function(b) { return b % 2 !== 0; };
  var addXf = {
    '@@transducer/step': add,
    '@@transducer/init': R.always(0),
    '@@transducer/result': R.identity
  };

  it('transduces into arrays', function() {
    eq(R.into([], R.map(add(1)), [1, 2, 3, 4]), [2, 3, 4, 5]);
    eq(R.into([], R.filter(isOdd), [1, 2, 3, 4]), [1, 3]);
    eq(R.into([], R.compose(R.map(add(1)), R.take(2)), [1, 2, 3, 4]), [2, 3]);
  });

  it('transduces into strings', function() {
    eq(R.into('', R.map(add(1)), [1, 2, 3, 4]), '2345');
    eq(R.into('', R.filter(isOdd), [1, 2, 3, 4]), '13');
    eq(R.into('', R.compose(R.map(add(1)), R.take(2)), [1, 2, 3, 4]), '23');
  });

  it('transduces into objects', function() {
    eq(R.into({}, R.identity, [['a', 1], ['b', 2]]), {a: 1, b: 2});
    eq(R.into({}, R.identity, [{a: 1}, {b: 2, c: 3}]), {a: 1, b: 2, c: 3});
  });

  it('dispatches to objects that implement `reduce`', function() {
    var obj = {x: [1, 2, 3], reduce: function() { return 'override'; }};
    eq(R.into([], R.map(add(1)), obj), 'override');
    eq(R.into([], R.filter(isOdd), obj), 'override');
  });

  it('allows custom transformer', function() {
    var intoSum = R.into(addXf);
    var add2 = R.map(add(2));
    var result = intoSum(add2);
    eq(result([1, 2, 3, 4]), 18);
  });

});