How to test stubbed database queries - node.js

Question

I have a Sails.Js controller that looks like this
module.exports = {
confirmID: function(req,res) {
var uid = req.params.id;
User.findOne({id:uid}).exec(function(err,user) {
// ...
});
}
}
where User is a sails-postgres model. I have tried testing it with mocha, sinon and supertest with a test like this
describe('Controller', function() {
var sandbox;
before(function() {
sandbox = sinon.sandbox.create();
sandbox.stub(User, 'findOne');
});
after(function() {
sandbox.restore();
});
describe('GET /confirmid/:id', function() {
it('should do something', function(done) {
request(sails.hooks.http.app)
.get('/confirmid/123')
.expect(200)
.end(function(err,res) {
sandbox.fakes[0].called.should.be.true;
done();
});
});
});
If I leave it at that it errors out because exec is called on undefined, but I can't seem to stub the nested exec method without either errors or the test hanging. Is there a way to stub a series of method calls such as .find().exec()? Or am I best to just leave this to integration tests where I can test it with an actual database?

Answer 1

Assuming that you really want to stub (not just spy) - you want to control what the query resolves to as opposed to simply knowing whether the query was executed. Here's what I'm using to stub sails/waterline query methods. Something like...
var stubQueryMethod = require('stubQueryMethod');
describe('Controller', function() {
before(function() {
stubQueryMethod(User, 'findOne', {
id: 123,
name: 'Fred Fakes'
});
});
after(function() {
User.findOne.restore();
});
describe('GET /confirmid/:id', function() {
it('should do something', function(done) {
request(sails.hooks.http.app)
.get('/confirmid/123')
.expect(200)
.end(function(err,user) {
user.should.have.property('name', 'Fred Fakes');
done();
});
});
});
});
Source: https://gist.github.com/wxactly/f2258078d802923a1a0d

Answer 2

For people looking for other options to stub or mock waterline models, I've found the following four options:
stubQueryMethod.js gist - https://gist.github.com/wxactly/f2258078d802923a1a0d
model mock gist - https://gist.github.com/campbellwmorgan/e305cc36365fa2d052a7
weaselpecker - https://github.com/ottogiron/weaselpecker
sails-mock-models - https://github.com/ryanwilliamquinn/sails-mock-models
After evaluating each one, I've decided on sails-mock-models because it is easy to understand and seems the most used sails mocking library according to npm: https://www.npmjs.com/package/sails-mock-models
Hope this helps someone!
Update: I'm still using sails-mock-models, and it is quite easy, but there are a few drawbacks such as it fails to return promises that are taken into a q.all(promiseArray).then() call. If I get around to investigating the other options or find a workaround, I will post it here.

Answer 3

This will only work for queries that use exec and it overloads all exec calls so if you try to return an error and you have, say, a controller with a policy out front, and the policy does a database lookup, you'll likely go into error there prior to hitting the controller code you intended to test.... that can be fixed with stub.onCall(x), but it is still a bit precarious.
Warnings aside, here's how I've done this in the past:
var path = require('path');
var sinon = require('sinon');
var Deferred = require(path.join(
process.cwd(),
'node_modules/sails',
'node_modules/waterline',
'lib/waterline/query/deferred'
));
module.exports = function () {
return sinon.stub(Deferred.prototype, 'exec');
};
Assuming you have the following service, MyService:
module.exports.dbCall = function (id, cb) {
Model.findOne(id).exec(function (err, result) {
if (err) {
sails.log.error('db calls suck, man');
return cb(err, null);
}
cb(null, result);
});
};
You can test the error case like so:
before(function () {
stub = databaseStub();
});
afterEach(function () {
stub.reset();
});
after(function () {
stub.restore();
});
it('should return errors', function (done) {
stub.onCall(0).callsArgWith(0, 'error');
MyService.dbCall(1, function (err, results) {
assert.equal(err, 'error');
assert.equal(results, null);
done();
});
});