fs.copy and fs.move for Node.JS

fs.extra.js

/*
  UPDATE: this has finally been pushed to npm as `fs.extra`
  URL: https://github.com/coolaj86/utile-fs/tree/master/fs.extra
*/
(function () {
  "use strict";
  
  console.warn('[Deprecated] See https://github.com/coolaj86/utile-fs');

  var fs = require('fs')
    , util = require('util')
    ;

  fs.copy = function (src, dst, cb) {
    console.warn('[Deprecated] See https://github.com/coolaj86/utile-fs');
    function copy(err) {
      var is
        , os
        ;

      if (!err) {
        return cb(new Error("File " + dst + " exists."));
      }

      fs.stat(src, function (err) {
        if (err) {
          return cb(err);
        }
        is = fs.createReadStream(src);
        os = fs.createWriteStream(dst);
        util.pump(is, os, cb);
      });
    }

    fs.stat(dst, copy);
  };

  fs.move = function (src, dst, cb) {
    console.warn('[Deprecated] See https://github.com/coolaj86/utile-fs');
    function copyIfFailed(err) {
      if (!err) {
        return cb(null);
      }
      fs.copy(src, dst, function(err) {
        if (!err) {
          // TODO 
          // should we revert the copy if the unlink fails?
          fs.unlink(src, cb);
        } else {
          cb(err);
        }
      });
    }

    fs.stat(dst, function (err) {
      if (!err) {
        return cb(new Error("File " + dst + " exists."));
      }
      fs.rename(src, dst, copyIfFailed);
    });
  };
}());

fs.extra.test.js

/*
  UPDATE: this has finally been pushed to npm as `fs.extra`
  URL: https://github.com/coolaj86/node-examples-js/tree/master/fs.extra
*/
(function () {
  "use strict";

  require('./fs.copy');

  var fs = require('fs')
    , sequence = require('futures').sequence()
    , exec = require('child_process').exec
    , count = 0
    ;

  function fsop(op, a, b, shouldpass) {
    var c = count;
    count += 1;
    return function (n) {
      function log(err) {
        if (shouldpass && !err) {
          console.log(c, op, a, b, 'passed');
          n();
        } else if (!shouldpass && err) {
          console.log(c, op, a, b, 'passed');
          n();
        } else {
          console.log(c, op, a, b, 'failed');
        }
      }

      fs[op](
          'file.' + a + '.t.txt'
        , 'file.' + b + '.t.txt'
        , log
      );
    };
  }

  sequence
    .then(function (next) {
      exec('rm ./file.*.t.txt; touch file.0.t.txt', next);
    })                               // 0
    .then(fsop('copy', 0, 1, true))  // 0, 1
    .then(fsop('copy', 0, 2, true))  // 0, 1, 2
    .then(fsop('copy', 0, 1, false)) // 0, 1, 2
    .then(fsop('copy', 3, 4, false)) // 0, 1, 2
    .then(fsop('move', 0, 3, true))  //    1, 2, 3
    .then(fsop('move', 0, 4, false)) //    1, 2, 3
    .then(fsop('move', 4, 0, false)) //    1, 2, 3
    .then(fsop('move', 5, 6, false)) //    1, 2, 3
    .then(fsop('move', 3, 0, true))  // 0, 1, 2
    .then(fsop('move', 2, 0, false)) // 0, 1, 2
    .then(function () {
      console.log('All Done.');
    });
}());

nice job!