nodejs/test/parallel/test-fs-readfile-pipe.js

// Copyright Joyent, Inc. and other Node contributors.
//
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// copy of this software and associated documentation files (the
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// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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'use strict';
const common = require('../common');

// simulate `cat readfile.js | node readfile.js`

if (common.isWindows || common.isAIX)
  common.skip(`No /dev/stdin on ${process.platform}.`);

const assert = require('assert');
const fs = require('fs');

const dataExpected = fs.readFileSync(__filename, 'utf8');

if (process.argv[2] === 'child') {
  fs.readFile('/dev/stdin', function(er, data) {
    assert.ifError(er);
    process.stdout.write(data);
  });
  return;
}

const exec = require('child_process').exec;
const f = JSON.stringify(__filename);
const node = JSON.stringify(process.execPath);
const cmd = `cat ${f} | ${node} ${f} child`;
exec(cmd, function(err, stdout, stderr) {
  assert.ifError(err);
  assert.strictEqual(stdout, dataExpected, 'it reads the file and outputs it');
  assert.strictEqual(stderr, '', 'it does not write to stderr');
  console.log('ok');
});