I have got myself to the stage of unit testing, and to be honest, with all the different examples online I have got myself confused. I have a good understanding of Mocha & Chai, but Sinon is a different story.
So I have what I think is a pretty straight forward setup. I have a POST route that calls a controller. This controller is like so (removed some basic validation code)
const { createUser } = require('../services/user.service');
const apiResponse = require('../helpers/apiResponse');
const postUser = async (req, res) => {
const user = {
account_id: req.body.id,
status: req.body.status,
created_at: new Date(),
updated_at: new Date(),
};
const result = await createUser(user);
return apiResponse.successResponseWithData(res, 'User added.', result.affectedRows);
} catch (err) {
return apiResponse.errorResponse(res, err);
}
};
module.exports = {
postUser,
};
So all it really does is validate, and then creates a user object with the req and pass that to a service class. This services class does nothing more than pass the data to a database class.
const { addUserToDb } = require('../database/user.db');
const createUser = async (user) => {
try {
const createdUser = await addUserToDb(user);
return createdUser;
} catch (err) {
throw new Error(err);
}
};
module.exports = {
createUser,
};
I wont show the database class because what I want to focus on first is the controller, and then I can hopefully do the rest myself.
So from what I understand, I should be testing functions. If a function makes an external call, I should spy, mock, stub that call? I should only spy, mock or stub this functions dependencies, if one of the dependencies
has its own dependency (like the service module above having a database call dependency), this should be performed in another test? Sorry, just a few questions to help me understand.
Anyways, so I have created a user.controller.test.js file. I have not got far with it, but this is what I have so far
const chai = require('chai');
const sinon = require('sinon');
const { expect } = chai;
const faker = require('faker');
const controller = require('../controllers/user.controller');
const service = require('../services/user.service');
const flushPromises = () => new Promise(setImmediate);
describe('user.controller', () => {
describe('postUser', () => {
beforeEach(() => {
//I see a lot of code use a beforeEach, what should I be doing here?
});
it('should create a user when account_id and status params are provided', async () => {
const req = {
body: { account_id: faker.datatype.uuid(), status: 'true' },
};
const stubValue = {
id: faker.datatype.id(),
account_id: faker.datatype.uuid(),
status: 'true',
created_at: faker.date.past(),
updated_at: faker.date.past(),
};
});
});
});
If I am being totally honest I am pretty lost as to what I should be testing here. From my understanding, I need to mock the service module I think.
Could someone kindly provide some insight as to what I should be doing in this test?
Many thanks
Update
Thank you for your detailed response, I have managed to get a spy working which is a step forward. So I want to do a test on my service module, createUser method.
You can see that my createUser method takes a user Object as a parameter and passes this to a database module where it is inserted into the database and then the user object returned.
So when testing my service class, I need to mock this call to my database module.
const chai = require('chai');
const sinon = require('sinon');
const { expect } = chai;
const faker = require('faker');
const service = require('../services/user.service');
const database = require('../database/user.db');
describe('user.service', () => {
describe('createUser', () => {
it('should create a user when user object is provided', async () => {
const user = {
id: faker.datatype.string(),
status: 'true',
created_at: faker.date.past(),
updated_at: faker.date.past(),
};
const expectedUser = {
id: user.id,
status: user.status,
created_at: user.created_at,
updated_at: user.updated_at,
};
const mockedDatabase = sinon.mock(database);
mockedDatabase.expects('addUserToDb').once().withArgs(expectedUser);
await service.createUser(user);
mockedDatabase.verify();
mockedDatabase.restore();
});
});
});
When I test this, I seem to be getting this response, and it still seems to be inserting the record into my database.
ExpectationError: Expected addUserToDb({
id: 'yX7AX\\J&gf',
status: 'true',
created_at: 2020-06-03T03:10:23.472Z,
updated_at: 2020-05-24T14:44:14.749Z
}, '[...]') once (never called)
at Object.fail (node_modules\sinon\lib\sinon\mock-expectation.js:314:25)
Do you have any idea what I am doing wrong?
Thanks
before I try, I would like to suggest to drop the try/catch blocks everywhere, I will assume you're using expressJs in your Node application, and for such, take a look at express-promise-router as using that Router (instead the default one) will automatically catch anything it was thrown and you just need to focus on the code...
taking your example, you would write:
const { addUserToDb } = require('../database/user.db');
const createUser = async (user) => addUserToDb(user);
module.exports = {
createUser,
};
and
const { createUser } = require('../services/user.service');
const apiResponse = require('../helpers/apiResponse');
const postUser = async (req, res) => {
const { id: account_id, status } = res.body;
const result = await createUser({ account_id, status }); // set the date in the fn
return apiResponse.successResponseWithData(res, 'User added.', result.affectedRows);
};
module.exports = {
postUser,
};
if there's an error and in some place on the route an error is thrown, you will get a nice message back in the response with the error
regarding the code it self, seems a lot cleaner to read - keep in mind that code is for humans, the machine does not even care how you name your variables 😊
Now, regarding the tests ... I do tend to split things into 3 parts
unit tests: the functions itself, single one, like validation, helpers, etc
integration tests: when you call your API endpoint what should be returned
GUI tests (or end-to-end/e2e): applied when a GUI exists, will skip this for now
so in your case, the first thing to make sure of is what are you testing... and taking that, start from the small blocks (unit tests) and move up to the blocks that make sure all is glued together (e2e)
So all it really does is validate, and then creates a user object with the req and pass that to a service class. This services class does nothing more than pass the data to a database class.
Seems a great way to start, so it "validates" ... let's test our validation, let's pass null, undefined, string when all you want is int and so on, until we get a pretty good idea that whatever it passes, we will reply correctly with and without an error
Note I tend to use OpenAPI specs, which makes things easier for me as it provides 2 things
documentation of the endpoints
validation of the endpoints with a nice error message to the consumer
and yes, I always test some validation just to make sure it's working as expected, even though I trust the tool 100% 😜
So from what I understand, I should be testing functions.
well, an application is a group of functions, so all good there 💪
If a function makes an external call, I should spy, mock, stub that call?
I'll try to explain as best as I can what spies, stubs and mocks in Sinon are, please be gentle 🙏
Spies
they tell us information about functions calls, like, number of times called, arguments, return value, and more - they have two types, anonymous spies or spies that wrap methods in our code
function testMyCallback(callback) { callback(); }
describe('testMyCallback fn', function() {
it('should call the callback', function() {
const callbackSpy = sinon.spy(); // anonymous spy - no arguments
testMyCallback(callbackSpy);
expect(callbackSpy).to.have.been.calledOnce;
});
});
const user = {
setNname: function(name) {
this.name = name;
}
}
describe('setname fn', function() {
it('should be called with name', function() {
const setNameSpy = sinon.spy(user, 'setName'); // wrap method spy
user.setName('Katie');
expect(setNameSpy).to.have.been.calledOnce;
expect(setNameSpy).to.have.been.valledWith('Katie');
setNameSpy.restore(); // to remove the Spy and prevent future errors
});
});
Stubs
are power-spies, as they have all the functionality of Spies, but they replace the target function, they have methods that can return a specific value or throw a specific exception and a bit more
they are great to be used with your question regarding external calls, as they replace calls (so you can mock the call behavior and never use the original call)
the simplest of the examples is:
function isAdult(age) {
return age > 21;
}
describe('Sinon Stub Example', () => {
it('should pass', (done) => {
const isAdult = sinon.stub().returns('something');
isAdult(0).should.eql('something');
isAdult(0).should.not.eql(false);
done();
});
});
we've STUB'ed our function, and explicitly said it's a "function" that returns a string something... and for now on, we will never need to go to the function itself, as we have STUB it, we've replaced the real behavior with our own
another example of using STUBs when calling our API application in our integration tests
describe('when we stub our API call', () => {
beforeEach(() => {
this.get = sinon.stub(request, 'get'); // stub "request.get" function
});
afterEach(() => {
request.get.restore(); // remove our power-spy
});
describe('GET /api/v1/accounts', () => {
const responseObject = {
status: 200,
headers: {
'content-type': 'application/json'
}
};
const responseBody = {
status: 'success',
data: [
{
accountId: 1,
status: 'active'
},
{
accountId: 2,
status: 'disabled'
}
]
};
it('should return all accounts', (done) => {
// the 3 objects of our callback (err, res, body)
this.get.yields(null, responseObject, JSON.stringify(responseBody));
request.get(`${base}/api/v1/movies`, (err, res, body) => {
expect(res.statusCode).to.be.eql(200);
expect(res.headers['content-type']).to.contain('application/json');
body = JSON.parse(body);
expect(body).to.be.an('array').that.includes(2);
done();
});
});
});
});
you can also stub axios, but you will need a new library, either moxios, or proxyquire or more...
Mocks
are a bit similar to Stubs (our Power-Spies) but they can be used to replace whole objects and alter their behavior, they are mostly used when you need to stub more than one function from a single object - if all you need is to replace a single function, a stub is easier to use
Mocks can make things oversimplify and you could break your application without even knowing, so be aware...
a normally use is, for example
function setupNewAccount(info, callback) {
const account = {
account_id: info.id,
status: info.status,
created_at: new Date(),
updated_at: new Date()
};
try { Database.save(account, callback); }
catch (err) { callback(err); }
}
describe('setupNewAccount', function() {
it('', function() {
const account = { account_id: 1, status: 'active' };
const expectedAccount = {
account_id: account.id, status: account.status
};
const database = sinon.mock(Database);
database.expectes('save').once().withArgs(expectedAccount);
setupNewAccount(account, function() {});
database.verify();
database.restore();
});
});
something that we will keep forgetting is the .restore() part, and for that, there's a package (one more...) called sinon-test that will auto cleanup at the end of a test
I just hope it helped you with some of your questions and it's a bit clearer now 😏
BTW, for stubbing HTTP requests, I use nock as I think it's much easier to read and use than Sinon, especially for anyone that is reading code for the first time and has no experience in either Sinon or Nock...
So I want to restore mongo database before tests begin.
I do this way:
const app = require("../app");
const chai = require("chai");
const mongoose = require("mongoose");
const User = require('../models/users');
const Region = require('../models/regions');
const testUsers = require('../testdata/users.json');
const testRegions = require('../testdata/regions.json');
describe('Restoring database', function () {
before(function(done) {
var promises = [
User.deleteMany().exec()
,Region.deleteMany().exec()
];
console.log('Cleaned database');
done();
});
before(function(done) {
testUsers.users.forEach(element => {
var ObjectId = mongoose.Types.ObjectId;
element._id = new ObjectId(element._id);
var newUser = new User(element);
newUser.save(function (err, result) {
if (err) {
console.log("err:",err);
}
});
});
console.log('Users added');
done();
});
before(function(done) {
testRegions.regions.forEach(element => {
var newRegion = new Region(element);
newRegion.save(function (err, result) {
if (err) {
console.log("err:",err);
}
});
});
console.log('Regions added');
done();
});
testdata/users.json and testdata/regions.json are simple json files including key/pair values.
Does this look good?
When I run
npm test
It does not give any error. And in the console I see this:
Restoring database
Cleaned database
Users added
Regions added
But when I look in database I get different results.
Sometimes everything looks good. All the rows are in the collections.
Sometimes a few rows are missing in one of the collections.
Sometimes one of the collections is empty.
This is a very strange behaviour.
I also tried to add in the variable "promises" each of the "newUser" and "newRegion" instead of executing them directly.
But I still get these strange results.
Whats the deal?
The issue is due to done() being called before the async statements/promises have completed.
Either use async/await or use Promises and only call done() when your async statements/promises have completed.
For example:
No done() call as we using await statements which will wait till each statement completes before continuing:
before(async function() {
let userResult = await User.deleteMany();
let regionResult = wait Region.deleteMany();
console.log('Cleaned database');
});
Or use done() with promises:
before(function(done) {
User.deleteMany()
.then(result => {
console.log('Cleaned database');
done();
});
});
The syntax in your before example is not adding Promises at all, it is simply adding those functions to an array:
var promises = [
User.deleteMany().exec()
,Region.deleteMany().exec()
];
Take a look at the following related answer to help.
I'm new to Mongoose. I wrote a statics method and a instance method for a Mongoose schema named 'questionSchema' and exported it like so:
var questionSchema = new Schema({
...
})
questionSchema.methods.createQuestion = function(){
return this.save(function(err){
if(err){
return err
};
return 'Saved the question';
});
};
questionSchema.statics.getAllQ = function(){
return this.find({}, function(err, res){
if(err){
return err
};
return res;
});
}
module.exports = mongoose.model('Question', questionSchema)
Then in a route in my Node/Express server, I imported the it as a model, and tried calling the static method, which should return all the documents under the Question model:
const Question = require('../models/question.js');
...
router.post('/qcrud/submit', (req, res) => {
let reqBody = req.body;
var newQuestion = new Question({reqBody});
newQuestion.createQuestion();
})
router.get('/qcrud/getAll',(req, res) => {
let qArr = Question.getAllQ()
res.send(qArr);
});
However, it returns a Query object, not an array like I expected. I looked around and saw on MDN that
'If you don't specify a callback then the API will return a variable
of type Query.'
I did specify a callback, but still got the Query object. First of all, am I using my static and instance methods right? Are the documents even saving? And how do I access the array documents saved?
If you're using Node 8.x you can utilize async/await
This way your code will look more synchronous:
questionSchema.statics.getAllQ = async () => {
return await this.find({});
}
router.get('/qcrud/getAll',async (req, res) => {
let qArr = await Question.getAllQ();
res.send(qArr);
});
You can find a really nice article that is explaining how to use Mongoose with async/await here.
I'm trying to use sinon or sinon-chai's calledWithNew (or simply called), but can't seem to get it to work, I've looked at a few suggestions online without luck either, here is the function I'm trying to test:
users.js
exports.create = function (data) {
//some validation
var user = new User(data);
return user.save().then((result) => {
return mailer.sendWelcomeEmail(data.email, data.name).then(() => {
return {
message: 'User created',
userId: result.id
};
});
}).catch((err) => {
return Promise.reject(err);
});
}
Here is my test:
users.test.js
beforeEach(() => {
saveStub = sandbox.stub(User.prototype, 'save').resolves(sampleUser);
spy = sandbox.spy(User);
});
afterEach(() => {
sandbox.restore();
});
it('should call user.save', async () => {
result = await users.create(sampleArgs);
expect(saveStub).to.have.been.called; //-> true
expect(spy).to.have.been.called; //-> false, calledWithNew returns same result as well
});
I found several posts suggesting spying on (window, 'className') but I'm using mocha, not a browser.
Trying to spy on (global, User / User.prototype) didn't work either.
User is a module-level variable in users.js. Sinon cannot affect it. When you do this in your test file:
spy = sandbox.spy(User);
You're creating a spy in the scope of your test file, sure, but your module is still using the original.
To do something like this, you need to export your constructor inside an object, then both invoke it and spy on it through that object:
Wherever User is coming from, let's say user.js:
class User {
// whatever your User implementation is
}
module.exports = { User };
users.js:
const userModule = require('./user');
...
var user = new userModule.User(data);
Then, in your test file:
const userModule = require('./user');
spy = sandbox.spy(userModule, 'User');
Another way to do this would be to use something like proxyquire. It can make these kinds of tests less obtrusive, but can make your tests more confusing to readers.
My preference is generally to keep constructors very simple so I don't ever have to spy on them. I've never used calledWithNew in any of my own projects for this reason. :\ It's up to you, though.
I get how to stub Mongoose models (thanks to Stubbing a Mongoose model with Sinon), but I don't quite understand how to stub calls like:
myModel.findOne({"id": someId})
.where("someBooleanProperty").equals(true)
...
.exec(someCallback);
I tried the following:
var findOneStub = sinon.stub(mongoose.Model, "findOne");
sinon.stub(findOneStub, "exec").yields(someFakeParameter);
to no avail, any suggestions?
I've solved it by doing the following:
var mockFindOne = {
where: function () {
return this;
},
equals: function () {
return this;
},
exec: function (callback) {
callback(null, "some fake expected return value");
}
};
sinon.stub(mongoose.Model, "findOne").returns(mockFindOne);
Take a look to sinon-mongoose. You can expects chained methods with just a few lines:
sinon.mock(YourModel).expects('findOne')
.chain('where').withArgs('someBooleanProperty')
.chain('exec')
.yields(someError, someResult);
You can find working examples on the repo.
Also, a recommendation: use mock method instead of stub, that will check the method really exists.
Another way is to stub or spy the prototype functions of the created Query (using sinon):
const mongoose = require('mongoose');
sinon.spy(mongoose.Query.prototype, 'where');
sinon.spy(mongoose.Query.prototype, 'equals');
const query_result = [];
sinon.stub(mongoose.Query.prototype, 'exec').yieldsAsync(null, query_result);
If you use Promise, you can try sinon-as-promised:
sinon.stub(Mongoose.Model, 'findOne').returns({
exec: sinon.stub().rejects(new Error('pants'))
//exec: sinon.stub(). resolves(yourExepctedValue)
});
I use promises with Mongoose and stub the methods like this:
const stub = sinon.stub(YourModel, 'findById').returns({
populate: sinon.stub().resolves(document)
})
Then I can call it like:
const document = await YourModel.findById.populate('whatever');
Using Multiple mongoose method stub using below code.
Service code
models.Match.findOne({ where: { id: ChangeInningInputType.id } })
.then((match) => {
if (!match) {
throw Error('Match not found');
}
models.Match.update(
{ inning: ChangeInningInputType.inning },
{ where: { id: ChangeInningInputType.id } },
);
return resolve(match);
})
.catch((error) => {
return reject(error);
});
Testcase code
it('Success test case for inning update', async () => {
const bulkCreateStub = sinon
.stub(models.Match, 'findOne')
.resolves(inningResponse);
const updateStub = sinon
.stub(models.Match, 'update')
.resolves(inningResponse);
const aa = await changeInning(
{},
{
ChangeInningInputType: inningRequest,
},
);
console.log('updateStub===>', updateStub);
expect(updateStub.calledOnce).to.equal(true);
expect(bulkCreateStub.calledOnce).to.equal(true);
});