I'm new to unit testing. My Web API project is MVC base on node-express-mongoose.
I have a conroller.js
as following:
const getComments = async (req, res) => {
let query = {};
try {
query = req.query.filter ? { email: new RegExp(`.*${req.query.filter}.*`, 'i') } : query;
const comments = await util.getComments(query);
return res.json(comments);
} catch (err) {
return res.status(500).send(`Internal server error: ${err}`);
}
};
The controller use util.js
function(s) which implements all database operations:
const comments = require('../models/comments');
exports.getComments = (query) => {
try {
return comments.find(query).sort({ createdAt: -1 });
} catch (err) {
throw err;
}
};
How do I create unit test using mocha & chai? Do I have to create fake mock using sinon etc?
If I want to write test on method that cannot be avoided without mocking of db I use mongodb-memory-server that acts as database and simulates mongodb behaviour.
const Comment = require('../models/comments');
const mockedComments = [ // modify example data depending on Your model
{userId: "1", body: "Mocked comment of user 1", createdAt: Date.now() },
{userId: "2", body: "Mocked comment of user 2", createdAt: Date.now() },
];
const getComments = require('../path/to/getComments');
const mongoose = require('mongoose');
const MongodbMemoryServer = require('mongodb-memory-server');
let mongoServer;
const opts = { useMongoClient: true };
before((done) => {
mongoServer = new MongodbMemoryServer();
mongoServer.getConnectionString()
.then((mongoUri) => {
return mongoose.connect(mongoUri, opts, (err) => {
if (err) done(err);
});
})
.then(() => {
// preparing in memory database contents
Promise.all([
Comment.create(mockedComments[0]),
Comment.create(mockedComments[1])
]).then(() => done());
});
});
after(() => {
mongoose.disconnect();
mongoServer.stop();
});
describe('getComments', () => {
it('successfully returns comments', async () => {
const result = await getComments({});
expect(result.length).to.equal(mockedComments.length);
});
it('successfully returns comments of user', async () => {
const result = await getComments({userId: 1});
expect(result[0].userId).to.equal(1);
});
});
Wait wait....
The question states that we are talking about "unit tests", so unit test are those ones where we assess the correct beahviour of the function/class/whatever WE have developed. Just this and anything else. Now, too bad I'm not a mongoDB dev, neither a mongo-memory-server contributor, so I don't really need to take into account these softwares in my tests. This is the reason test doubles (stubs/mocks/spies) were born and we, as good software engineers, should make a wise use of them
so, this is my unit test:
const {expect} = require("chai") const sinon = require("sinon") const uut = require("./users.service") const UserModel = require("./user.model") it("given correct userId should retrieve users full name" , async () => { //given const fixture = { _id : "fakeuser", name: "Fake", surname: "User" } let stub = sinon.stub(UserModel , "findById").returns(fixture) //when let result = await uut.getUserFullnameById(fixture._id) //then expect(result).to.eq("Fake User") stub.restore() })
This test tell me that getUserFullnameById function behaves correctly,
const User = require("./user.model") module.exports.getUserFullnameById = async function (userId) { let user = await User.findById(userId) return `${user.name} ${user.surname}` }
I isolate my logic from mongoose because I don't need to know if mongoose works and I'm able to connect to a underlying mongodb instance. So someone could point that my test passes even if there is no "findById" API in mongoose library, so that's why I rely on integration tests as well
describe("integration test" , () => { const mongoose = require("mongoose") before(()=> { mongoose.connect("mongodb://localhost:27017/db" , { useNewUrlParser: true , useUnifiedTopology: true}) mongoose.Promise = global.Promise }) beforeEach(async ()=> { await mongoose.connection.dropDatabase() }) it("given correct userId should retrieve users full name" , async () => { let fixture = new UserModel({name : "Fake" , surname : "User"}) await fixture.save() let result = await uut.getUserFullnameById(fixture._id) expect(result).to.eq("Fake User") }) })
the integration test does the same thing as before, but does it whithin a context. if i mess around with my method under test, I could break the integration test and i will know that I am misusing mongoose or mongodb connection, or I can break both, so I know that I am likely just disrespecting my business rules. Another advantage: integration tests are slow and brittle, but I can provide quality code even providing less of them and adding more isolated unit tests
Now you have two more cases: first name not present and last name not present: how do you test and extend your code?
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.