`this.slow()` doesn't work in describe callbacks like `this.timeout`

[Macil]

describe('a', function() {
  this.timeout(5000);
  this.slow();

  it('1', function(cb) {
    setTimeout(cb, 3000);
  });

  it('2', function(cb) {
    this.slow(); // just for contrast with test 1
    setTimeout(cb, 3000);
  });
});

If I understand the docs correctly, I expect neither of the tests to timeout or have slow warnings because they're both covered by this.timeout and this.slow calls in the describe section. Neither of the tests timeout, but the first test (not covered by its own redundant this.slow) has a slow warning still:

  a
    ✓ 1 (3008ms)
    ✓ 2


  2 passing (6s)

mocha version 2.5.3

[boneskull]

this.slow() doesn't do anything except return the current setting. You'll need to give it a parameter.

[Macil]

I'm confused because in test 2, calling this.slow() causes it to not show the slow warning without a parameter given. Removing it causes this output:

  a
    ✓ 1 (3006ms)
    ✓ 2 (3001ms)


  2 passing (6s)

[boneskull]

OK, thanks. that's a bug. this is mostly for my benefit, but the explanation:

Runnable.prototype.slow = function(ms) {
  if (!arguments.length) {
    return this._slow;
  }
  if (typeof ms === 'string') {
    ms = milliseconds(ms);
  }
  debug('timeout %d', ms);
  this._slow = ms;
  return this;
};

When you call this.slow() from a test, it calls this:

Context.prototype.slow = function(ms) {
  this.runnable().slow(ms);
  return this;
}

If the latter function is called without a parameter, Runnable.prototype.slow() will have arguments equal to [undefined]. The fix is to test ms explicitly.