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x/ramda/test/mergeWithKey.js

:ram: Practical functional Javascript
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var assert = require('assert');
var R = require('../source');var eq = require('./shared/eq');

describe('mergeWithKey', function() { function last(k, x, y) { return y; }
it('takes two objects, merges their own properties and returns a new object', function() { var a = {w: 1, x: 2}; var b = {y: 3, z: 4}; eq(R.mergeWithKey(last, a, b), {w: 1, x: 2, y: 3, z: 4}); });
it('applies the provided function to the key, the value from the first object' + ' and the value from the second object to determine the value for keys that' + ' exist in both objects', function() { var a = {a: 'b', x: 'd'}; var b = {a: 'c', y: 'e'}; var c = R.mergeWithKey(function(k, a, b) { return k + a + b; }, a, b); eq(c, {a: 'abc', x: 'd', y: 'e'}); });
it('is not destructive', function() { var a = {w: 1, x: 2}; var res = R.mergeWithKey(last, a, {x: 5}); assert.notStrictEqual(a, res); eq(res, {w: 1, x: 5}); });
it('reports only own properties', function() { var a = {w: 1, x: 2}; function Cla() {} Cla.prototype.x = 5; eq(R.mergeWithKey(last, new Cla(), a), {w: 1, x: 2}); eq(R.mergeWithKey(last, a, new Cla()), {w: 1, x: 2}); });
});