node/test/parallel/test-util-log.js

'use strict';
require('../common');
var assert = require('assert');
var util = require('util');

assert.ok(process.stdout.writable);
assert.ok(process.stderr.writable);

var stdout_write = global.process.stdout.write;
var strings = [];
global.process.stdout.write = function(string) {
  strings.push(string);
};
console._stderr = process.stdout;

var tests = [
  {input: 'foo', output: 'foo'},
  {input: undefined, output: 'undefined'},
  {input: null, output: 'null'},
  {input: false, output: 'false'},
  {input: 42, output: '42'},
  {input: function() {}, output: '[Function]'},
  {input: parseInt('not a number', 10), output: 'NaN'},
  {input: {answer: 42}, output: '{ answer: 42 }'},
  {input: [1, 2, 3], output: '[ 1, 2, 3 ]'}
];

// test util.log()
tests.forEach(function(test) {
  util.log(test.input);
  const result = strings.shift().trim();
  const re = (/[0-9]{1,2} [A-Z][a-z]{2} [0-9]{2}:[0-9]{2}:[0-9]{2} - (.+)$/);
  const match = re.exec(result);
  assert.ok(match);
  assert.equal(match[1], test.output);
});

global.process.stdout.write = stdout_write;