This library is done to simplify creation of integration tests for node.js application with Mongo DB. I starts local mongodb process using mongodb-memory-server library, and it work in "InMemory" mode, which improve performance of your tests.
Since running embedded mongo takes some time, we need to config mocha
to wait until mongo is up and running, the easiest way to do it add --delay
flag for mocha
and handle async flow, like this
//package.json
...
"scripts": {
...
"test": "mocha ./**/*.spec.js --delay",
...
},
...
add init.spec.js
//init.spec.js
const mongoUnit = require('mongo-unit')
mongoUnit.start().then(() => {
console.log('fake mongo is started: ', mongoUnit.getUrl())
process.env.DATABASE_URL = mongoUnit.getUrl() // this var process.env.DATABASE_URL = will keep link to fake mongo
run() // this line start mocha tests
})
after(() => {
const dao = require('./dao')
console.log('stop')
dao.close()
return mongoUnit.stop()
})
Code under test
//dao.js
const mongoose = require('mongoose')
const userSchema = new mongoose.Schema({
name: String,
})
const taskSchema = new mongoose.Schema({
userId: String,
task: String,
})
module.exports = {
init: () => mongoose.connect(process.env.DATABASE_URL),
close: () => mongoose.disconnect(),
User: mongoose.model('user', userSchema),
Task: mongoose.model('task', taskSchema),
}
Test data
{
"users": [
{
"_id": "56d9bf92f9be48771d6fe5b1",
"name": "test"
},
{
"_id": "56d9bf92f9be48771d6fe5b2",
"name": "John"
}
],
"tasks": [
{
"userId": "56d9bf92f9be48771d6fe5b1",
"task": "do stuff"
},
{
"userId": "56d9bf92f9be48771d6fe5b1",
"task": "fix stuff"
}
]
}
Mocha test
//dao.spec.js
const {expect} = require('chai')
const mongoUnit = require('mongo-unit')
const testData = require('./data.json')
const daoUT = require('./dao')
describe('dao', ()=>{
before(() => daoUT.init())
beforeEach(() => mongoUnit.load(testData))
afterEach(() => mongoUnit.drop())
it('should find all users', () => {
return daoUT.User.find()
.then(users => {
expect(users.length).to.equal(2)
expect(users[0].name).to.equal('test')
})
})
it('should find all tasks for user 1', () => {
return daoUT.User.find()
.then(users => users[0])
.then(user=>daoUT.Task.find({userId: user._id}))
.then(tasks => {
expect(tasks.length).to.equal(2)
expect(tasks[0].task).to.equal('do stuff')
})
})
})
I was inspired by dbUnit library, which is very popular in java world.
There is alternative library for mocking Mongo: mockgoose
It works on Node.js 12+
npm install -D mongo-unit
docker build -t mongo-unit .
docker run -it mongo-unit
It starts mongod on one of available port and returns Promise with URL to connect to this db.
opts
is optional params, you can specify some command line params for mongod:
opts.port
- preferable mongo db port, default:27017
opts.dbName
- name of test db, default:test
opts.dbpath
- db path, default:<node_modules/mongo-unit>\.mongo-unit
opts.verbose
- enable debug logs, default:false
opts.version
- specify which version of mongo to download. e.g.version=v3.6
opts.useReplicateSet
- specify we want to start the memory server as aMongoMemoryReplSet
needed to support transactions, default:false
opts.storageEngine
- specify the Mongo storage engine to use (e.g.,wiredTiger
); default: non-replica setephemeralForTest
, replica setwiredTiger
. (Note that as of Mongo 7+,ephemeralForTest
is no longer supported or allowed, so you will have to specify an option here.)
mongodb-memory-server can also be configured via environment variables.
For instance, export MONGOMS_DEBUG=1
will activate debug logging in the memory server. See their docs for more information.
It stops mongod process
Syncronius API returns URL to connect to test db, if test DB is not started it thows an Exception
Inserts given data (like below) DB collections, returns Promise.
{
"collectionName1":[
{"field1":"value1"},
{"field2":"value2"}
],
"collectionName2":[
{"field3":"value3"},
{"field4":"value4"}
]
}
Clear collections based on given data (data format is the same), returns Promise.
Drops test DB, returns Promise.
helper function, load db data into mongo
helper function, clear all db data from mongo