const f = (a,b) => a+b;
// proptest
const QC = require('proptest');
const property = QC.createProperty((label, r) => { r(); })
try {
property(
'is commutative',
QC.nat.array(),
x => x.indexOf(8) === -1);
} catch(err) { console.log(err); }
// fast-check
const fc = require('fast-check');
try {
fc.assert(
fc.property(
fc.array(fc.nat()),
x => x.indexOf(8) === -1));
} catch(err) { console.log(err); }