用 Sinon 构建 Mongoose 模型

Question

I want to create a stub for the Mongoose save method in a particular model, so that any instance of my model I create will call the stub instead of the normal Mongoose save method. My understanding is that the only way to do this is to stub the entire model like this:

var stub = sinon.stub(myModel.prototype);

Unfortunately, this line of code causes my tests to throw the following error:

TypeError: Cannot read property 'states' of undefined

Does anyone know what is going wrong here?

Answer 1

There are two ways to accomplish this. The first is

var mongoose = require('mongoose');
var myStub = sinon.stub(mongoose.Model, METHODNAME);

If you console log mongoose.Model you will see the methods available to the model (notably this does not include lte option).

The other (model specific) way is

var myStub = sinon.stub(YOURMODEL.prototype.base.Model, 'METHODNAME');

Again, the same methods are available to stub.

EDIT: Some methods such as save are stubbed as follows:

var myStub = sinon.stub(mongoose.Model.prototype, METHODNAME);
var myStub = sinon.stub(YOURMODEL.prototype, METHODNAME);

Answer 2

Take a look to sinon-mongoose . You can expects chained methods with just a few lines:

sinon.mock(YourModel).expects('find')
  .chain('limit').withArgs(10)
  .chain('exec');

You can find working examples on the repo.

Also, a recommendation: use mock method instead of stub , that will check the method really exists.

Answer 3

save is not a method on the model, it's a method on the document (instance of a model). Stated here in mongoose docs .

Constructing documents

Documents are instances of our model. Creating them and saving to the database is easy

Therefore, it will always be undefined if you're using your model to mock a save()

Going along with @Gon's answer, using sinon-mongoose & factory-girl with Account being my model:

Will not work

var AccountMock = sinon.mock(Account)

AccountMock
  .expects('save') // TypeError: Attempted to wrap undefined property save as function
  .resolves(account)

Will work

var account = { email: 'sasha@gmail.com', password: 'abc123' }

Factory.define(account, Account)
Factory.build('account', account).then(accountDocument => {
  account = accountDocument

  var accountMock = sinon.mock(account)

  accountMock
    .expects('save')
    .resolves(account)

  // do your testing...
})

Answer 4

Instead of the whole object, try:

sinon.stub(YOURMODEL.prototype, 'save')

Make sure YOURMODEL is the class not the instance.

Answer 5

Tangentially-related, but relevant...

I needed to mock a custom model method like:

myModelSchema.methods.myCustomMethod = function() {....}

To create a stub I did:

myCustomMethodStub = sinon.stub(MyModel.schema.methods, 'myCustomMethod').callThrough();

Answer 6

As told by djv, the save method is on the document. So you can stub it this way:

const user = new User({
      email: 'email@email.com',
      firstName: 'firstName',
      lastName: 'lastName',
      userName: 'userName',
      password: 'password',
    });

stub(user, 'save').resolves({ foo: 'bar' });

Bonus, you can assert it with Chai and Chai as promised this way:

const promise = user.save();
await chai.assert.doesNotBecome(promise, { foo: 'bar' });