Trigger a beforeCreate middleware before inserting a new document

[pypmannetjies]

This middleware is similar to the beforeOverwrite, but it does not have a query since it is a brand new document

[coveralls]

Coverage increased (+0.03%) to 91.572% when pulling 7b4e212 on add-create-middleware into e22ef94 on master.

[alecgibson]

I don't know if we can clarify that this is talking about creating a MongoDB document (not a ShareDB document, which might be "created" with a version > 1).

I guess it's probably fine, so long as all of our actions are talking specifically about MongoDB operations (which I guess is already implied with beforeOverwrite, and differentiated in beforeSnapshotLookup)

[alecgibson]

(I also can't help but wonder if this could have just been a "special case" of beforeOverwrite (maybe renamed beforeWrite), where query happens to be null, but I guess it's a bit late for that now anyway.)

[alecgibson]

Also, as discussed, this is probably all fine.

[pypmannetjies]

As discussed in the weekly meeting, I do still like it this way but open to adding another middleware for both at some point!

[alecgibson]

This function feels weird to me:

• it uses magic strings
• it assumes it's the only assertion, which is always run at the end (what if I want to assert many things?)

I'd normally prefer something like:

describe('', () => {
  var docId;

  beforeEach(() => {
    docId = 'test1';
  });

  function expectStuff() {
    // has access to docId
  }
});

But better yet, can't we just make a helper method:

function docCount(collection, id, cb) {
  var query = {_id: id};
  db.query('collection', query, null, null, function(err, results) {
    var count = null;
    if (!err) count = results.length;
    cb(err, count);
  }
}

Still has some boilerplate in the code itself, but that's the sad fact of callbacks, I guess:

docCount(collection, id, function(error, count) {
  if (error) return done(error);
  expect(count).to.equal(0);
  return done();
});

[pypmannetjies]

As discussed, will fix this in another PR