Creating stub for sequeilze models with association - node.js

Question

I am using mocha and chai for writing test for RESTful APIs
I have read some articles where people suggests to create stubs for queries, and you shouldn't be actually making a database query.
But How would I make sure if it works?
See below controller.
const Op = require('sequelize').Op
//Models
const {
Item,
Location,
Combo,
Service,
ComboItem,
ItemLocation
} = require('../models')
const _ = require('lodash')
//Services
const paginate = require('../services/PaginationService')
const getAllItems = async function(req, res) {
if(req.query.location_id){
let items
const item = await Location.findOne({
where: {
id: 1
},
include: {
model: Item,
through: {
model: ItemLocation,
attributes: []
},
as: 'itemsAtLocation',
include: [
{
model: Service,
as: 'service',
attributes: ["id"]
},
{
model: Combo,
as: 'combo',
attributes: ["start_date", "expiry_date"]
}
]
}
})
if(!item)
return res.status(200).send({
status: true,
message: "No item found at location!",
data: {}
})
items = item.itemsAtLocation
let data = {}
data.services = []
data.combos = []
_.forEach(items, item => {
let itemData = {
id: item.id,
name: item.name,
price: item.price,
discount_per: item.discount_per,
}
if(item.service)
data.services.push(itemData)
if(item.combo) {
itemData.start_date = item.combo.start_date
itemData.expiry_date = item.combo.expiry_date
data.combos.push(itemData)
}
})
return res.status(200).send({
status: true,
message: "Successfully fetch all items!",
data: data
})
} else {
const items = await Item.findAll({
include: [
{
model: Service,
as: 'service',
attributes: ["id"]
},
{
model: Combo,
as: 'combo',
attributes: ["start_date", "expiry_date"]
}
],
attributes: ["id", "name", "price", "discount_per", "description"],
...paginate(+req.query.page, +req.query.per_page)
})
let data = {}
data.services = []
data.combos = []
_.forEach(items, item => {
let itemData = {
id: item.id,
name: item.name,
price: item.price,
discount_per: item.discount_per,
}
if(item.service)
data.services.push(itemData)
if(item.combo) {
itemData.start_date = item.combo.start_date
itemData.expiry_date = item.combo.expiry_date
data.combos.push(itemData)
}
})
return res.status(200).send({
status: true,
message: "Successfully fetch all items!",
data: data
})
}
}
module.exports = {
getAllItems
}
As you can see from above code. I need queries to return data in a specific form. If it won't be in that form things won't work.
Can someone suggest how can I create stubs for such kind of functions so that structure also be preserved?
Below is the test that I have wrote, But it uses actual db calls.
describe('GET /api/v1/items', function () {
it('should fetch all items orgianized by their type', async () => {
const result = await request(app)
.get('/api/v1/items')
.set('Accept', 'application/json')
.expect('Content-Type', /json/)
.expect(200)
expect(result)
.to.be.a('Object')
expect(result.body.status)
.to.be.a('Boolean').true
expect(result.body.data, "data should be an Object and every key should an Array")
.to.satisfy(data => {
expect(data).to.be.a('Object')
.to.not.be.null
if(!_.isEmpty(data)) {
expect(data).to.have.any.keys('services', 'combos')
_.forOwn(data, (value, key) => {
expect(data[key]).to.be.a('Array')
})
return true
}
return true
})
})
})

Answer 1

One way you can do that is by stubbing the methods from your models, i.e. Location.findOne and Item.findAll. So your tests could look a bit like the code below:
const sinon = require('sinon');
const Location = require('../models/location'); // Get your location model
const Item = require('../models/item'); // Get your item model
describe('myTest', () => {
let findOneLocationStub;
let findAllItemsStub;
beforeEach(() => {
findOneLocationStub = sinon.stub(Location, 'findOne');
findAllItemsStub = sinon.stub(Item, 'findAll');
});
afterEach(() => {
findOneLocationStub.verifyAndRestore();
findAllItemsStub.verifyAndRestore();
});
it('returns 200 when location not found', () => {
findOneLocationStub.resolves(null);
expects...
});
});
I did not run the test, but something like that should work. But note that I had to split the models into their own file to do the stub. Probably there's a way to do the same using your current implementation.
Another thing I would suggest is having some kind of use case into your method that is responsible for database implementation. Something like:
const getAllItemsUseCase = (params, queryService) => {
if(params.locationId){
let items
const item = await queryService.findOneLocation({
};
So when you call this method from your controller, you can do call:
const getAllItems = async function(req, res) {
const params = {
locationId: req.query.location_id,
// and more parameters
};
const queryService = {
findOneLocation: Location.findOne,
};
const results = await getAllItemsUseCase(params, queryService);
}
This way you will detach your business logic from the controller and you will have a much easier time to mock your query: you just change the methods provided to queryService.
You can find some interesting read from this blog post: https://blog.cleancoder.com/uncle-bob/2012/08/13/the-clean-architecture.html