node/test/parallel/test-stdout-to-file.js

'use strict';
const common = require('../common');
const assert = require('assert');
const path = require('path');
const childProcess = require('child_process');
const fs = require('fs');

const scriptString = path.join(common.fixturesDir, 'print-chars.js');
const scriptBuffer = path.join(common.fixturesDir,
                               'print-chars-from-buffer.js');
const tmpFile = path.join(common.tmpDir, 'stdout.txt');

common.refreshTmpDir();

function test(size, useBuffer, cb) {
  var cmd = '"' + process.argv[0] + '"' +
            ' ' +
            '"' + (useBuffer ? scriptBuffer : scriptString) + '"' +
            ' ' +
            size +
            ' > ' +
            '"' + tmpFile + '"';

  try {
    fs.unlinkSync(tmpFile);
  } catch (e) {}

  console.log(`${size} chars to ${tmpFile}...`);

  childProcess.exec(cmd, common.mustCall(function(err) {
    assert.ifError(err);
    console.log('done!');

    var stat = fs.statSync(tmpFile);

    console.log(`${tmpFile} has ${stat.size} bytes`);

    assert.strictEqual(size, stat.size);
    fs.unlinkSync(tmpFile);

    cb();
  }));
}

test(1024 * 1024, false, common.mustCall(function() {
  console.log('Done printing with string');
  test(1024 * 1024, true, common.mustCall(function() {
    console.log('Done printing with buffer');
  }));
}));