mongoose-mock

Note that the landtech fork has deviated quite some way from the original.

Usage

Require as:

var mongooseMock = require('@landtech/mongoose-mock');

From the point at which this is required, any code that calls require('mongoose') will return mongooseMock. This even works across npm-link boundaries. Note that in order to ensure this happens before any tests, put this statement in a mocha-startup.js file and then create a mocha.opts file with the following content:

--require test/mocha-startup.js

If you are just running a test on one file this is not necessary, but if you are running tests recursively (or whatever), then you need the require to be called first.

mongooseMock provides stubs with sinon for all(ish) of the methods you code might need to call. You can provide custom return values for each of them, or leave them with the defaults (which are null in most cases).

Lets look at a full example of usage in a testing file:

var mongooseMock = require('mongoose-mock'),
    proxyquire = require('proxyquire'),
    expect = require('chai').expect,
    sinon = require('sinon');

// see proxyquire docs for why you might want this rather than just require
var ThingToTest = proxyquire('../thing-to-test', {});

// the mock models were loaded as children of the above module, and are now available...
var SomeModel = mongooseMock.model('SomeModel'); 
var AnotherModel = mongooseMock.model('AnotherModel');

describe('ThingToTest', function () {
  var sandbox;
  beforeEach(() =>{
    sandbox = sinon.sandbox.create();
    SomeModel.useSandbox(sandbox);
    AnotherModel.useSandbox(sandbox);
  });

  it('does a thing', (done) => {
    SomeModel.findOne.yields(null, new SomeModel({whatever: 'trevor'}));
    ThingToTest.doAThing("please", result => {
      expect(SomeModel.findOne.callCount).to.eql(1);
      expect(SomeModel.update.getCall(0).args[1]).to.eql({madness: 'this-way'});
      expect(AnotherModel.find.callCount).to.eql(0);
    });
  });
});

Note how we set a new sandbox before each test - you can read about sandboxes in sinon's documentation. Note that in order to make it work here we had to do some slightly hacky stuff - but all you need to know is that you call useSandbox.

Note that if the code being tested is of the following form, i.e. the mongoose stuff ends in a then call (i.e. it looks like a Promise):

  SomeModel.find({}).populate({}).sort({}).then(res => {
    // do something with res
  })

Then, in your test, you need the last non-then method (in this case sort) to return a thenable...

  var SomeModel = mongooseMock.model('SomeModel');
  SomeModel.sort.returns(Promise.resolve("some results"));

Developing

If you run into problems using this module, it's likely that you are trying to use a feature that doesn't exist yet. Hopefully it will be easy to add!

I recommend using npm link during development.