mocha didn't work when using fs.readFile or fs.writeFile

[cwchentw]

mocha 2.2.4
I tried assert, expect.js, and should.js. All the three assert modules didn't work in mocha when they were called in fs.readFile or fs.writeFile. My test file is in this gist post.

[a8m]

PTAL on testing asynchronous code example and let me know if there's any problems.
Thanks.

Update:
based on your gist, this example should be something like that:

describe('Test on I/O', function() {
  it('write test', function(done) {
    fs.writeFile('./text.txt', "Hello Node.js" + os.EOL, function(err) {
      if (err) {
        throw "Unable to read file";
      }
      expect(3).to.equal(4); // Should fail
      done();
    });
  });

  it('read test', function(done) {
    fs.readFile('./file.txt', function(err, data) {
      if (err) {
        throw "Unable to read file";
      }
      expect(3).to.equal(4); 
      done();
    });
  });
});

[cwchentw]

Add done() function solved the problem. Thanks a lot.

[syedirfan7]

@a8m how do i test it without failing the test ? i mean i want to pass my test instead of failing it

[plroebuck]

I would do it like this...

var assert = require('assert');
var fs = require('fs');
var os = require('os');
var path = require('path');
var util = require('util');

describe('File I/O', function() {
  var pathname;
  var content = "Howdy";

  before(function() {
    var filename = util.format('io-testfile-mocha-%s.txt', process.pid);
    pathname = path.join(os.tmpdir(), filename);
  });

  it('should write to file', function(done) {
    fs.writeFile(pathname, content, function(err) {
      if (err) {
        return done(err);
      }
      done();
    });
  });

  it('should read from file', function(done) {
    fs.readFile(pathname, function(err, data) {
      if (err) {
        return done(err);
      }
      assert.strictEqual(data, content);
      done();
    });
  });

  after(function() {
    fs.unlinkSync(pathname);
  });
});