chai 621

const chai= require("chai"); assert= chai.assert; var obj = { val: 10 }; var decFn = function() { obj.val-=2; }; assert.decreases(decFn, obj, 'val'); assert.decreasesBy(decFn, obj, 'val', '2'); //assert.decreasesButNotBy(()=> { obj.val++; }, obj, 'val', 'x'); assert.decreasesButNotBy(decFn, obj, 'val', '3');