Develop Reference

js imported function error "getUser not a function"

I have three files
BotJobActions.js
TestDate.js
CreateCron.js
The BotJobActions file creates a function called getUser that returns the user connected to a specific job, then exports the getUser along with a bunch of other functions.
const getUser = async (jobId) =>{
await mongoConnect(process.env.DB_PWORD)
try {
const user = await User.findOne({pendingJobs:jobId})
return user
} catch (err) {
console.log(err)
}
}
module.exports = { newJob, getUserJobs, getUser, updateUserJob, destroyUserPendingJob, destroyUserCompletedJob, activateJob, deactivateJob, endJob }
TestDate defines a function called runBot which runs a bot Job. In runBot it also calls the getUser function, so I can make changes to a specific user. Then exports the function because it will be used in other files.
const { getUser } = require("../bot/botJobActions");
const runBot = async (todayJobs) =>{
// await mongoConnect(process.env.DB_PWORD)
for(const job of todayJobs){
const clubPassword = decryptToken(job.clubPassword.token, job.clubPassword.iv)
const user = await getUser(job.id)
if(job.proxy){
const proxyConfig = await getProxyConfig(user)
if(proxyConfig.status === "no proxy") console.log("[-] Proxy Config Retrival Error/Running Without Proxy")
// await startBot(member=job.member?job.member : null, proxy=proxyConfig.status === 'success'?proxyConfig:null, job.clubUsername, clubPassword, job.startTime, job.endTime, job.courseList, job.id)
await console.log(member=job.member?job.member : null, proxy=proxyConfig.status === 'success'?proxyConfig:null, job.clubUsername, clubPassword, job.startTime, job.endTime, job.courseList, job.id)
}else{
// await startBot(member=job.member?job.member : null, proxy=null, job.clubUsername, clubPassword, job.startTime, job.endTime, job.courseList, job.id)
await console.log(member=job.member?job.member : null, proxy=null, job.clubUsername, clubPassword, job.startTime, job.endTime, job.courseList, job.id)
}
}
return
}
module.exports = { runBot, getJobs }
CreateCron is a function that runs whenever a job is created with a specific start time. This function will create a cron job for that specified time to run the bot.
const schedule = require('node-schedule');
const { runBot } = require('./testDate');
const createCron = (job) =>{
const startDate = new Date(job.botStartDate)
const startTime = new Date(`09/19/2000 ${job.botStartTime}`)
startDate.setHours(startTime.getHours())
startDate.setMinutes(startTime.getMinutes())
console.log(startDate.toUTCString())
schedule.scheduleJob(startDate, async function(){
console.log('run job')
await runBot([job])
})
}
My problem thought is that whenever I run the createCron function, I get an error saying that the getUser is not a function. Even thought it is.
Any help is appreciated!!

I was able to fix the problem. All I had to do was use the absolute path to the function instead of the relative path. Then the functions worked. Hope this can help somebody!

How to mock fs module together with unionfs?

I have written a test case that successfully load files into virtual FS, and at the same time mounted a virtual volume as below
describe("should work", () => {
const { vol } = require("memfs");
afterEach(() => vol.reset());
beforeEach(() => {
vol.mkdirSync(process.cwd(), { recursive: true });
jest.resetModules();
jest.resetAllMocks();
});
it("should be able to mock fs that being called in actual code", async () => {
jest.mock("fs", () => {
return ufs //
.use(jest.requireActual("fs"))
.use(createFsFromVolume(vol) as any);
});
jest.mock("fs/promises", () => {
return ufs //
.use(jest.requireActual("fs/promises"))
.use(createFsFromVolume(vol) as any);
});
const { createFsFromVolume } = require("memfs");
const { ufs } = require("unionfs");
const { countFile } = require("../src/ops/fs");
vol.fromJSON(
{
"./some/README.md": "1",
"./some/index.js": "2",
"./destination": null,
},
"/app"
);
const result = ufs.readdirSync(process.cwd());
const result2 = ufs.readdirSync("/app");
const result3 = await countFile("/app");
console.log({ result, result2, result3 });
});
});
By using ufs.readdirSync, I can access to virtual FS and indeed result giving me files that loaded from disc into virtual FS, result2 representing /app which is a new volume created from vol.fromJSON.
Now my problem is I am unable to get the result for result3, which is calling countFile method as below
import fsPromises from "fs/promises";
export const countFile = async (path: string) => {
const result = await fsPromises.readdir(path);
return result.length;
};
I'm getting error
Error: ENOENT: no such file or directory, scandir '/app'
which I think it's because countFile is accessing the actual FS instead of the virtual despite I've had jest.mock('fs/promises')?
Please if anyone can provide some lead?

This is the function you want to unit test.
//CommonJS version
const fsPromises = require('fs/promises');
const countFile = async (path) => {
const result = await fsPromises.readdir(path);
return result.length;
};
module.exports = {
countFile
}
Now, how you would normally go about this, is to mock fsPromises. In this example specifically readdir() since that is the function being used in countFile.
This is what we call: a stub.
A skeletal or special-purpose implementation of a software component, used to develop or test a component that calls or is otherwise dependent on it. It replaces a called component.
const {countFile} = require('./index');
const {readdir} = require("fs/promises");
jest.mock('fs/promises');
beforeEach(() => {
readdir.mockReset();
});
it("When testing countFile, given string, then return files", async () => {
const path = "/path/to/dir";
// vvvvvvv STUB HERE
readdir.mockResolvedValueOnce(["src", "node_modules", "package-lock.json" ,"package.json"]);
const res = await countFile(path);
expect(res).toBe(4);
})
You do this because you're unit testing. You don't want to be dependent on other functions because that fails to be a unit test and more integration test. Secondly, it's a third-party library, which is maintained/tested by someone else.
Here is where your scenario applies. From my perspective, your objective isn't to test countFile() rather, to test fsPromises and maybe test functionality to read virtual file-systems: unionfs. If so then, fsPromises doesn't need to really be mocked.

Unable to implement singleton patten in javascript

I am trying to implement a singleton pattern for the fastify instance. My code is as follows :-
const { createFastifyServer: server } = require("../app");
const getFastifyInstance = (() => {
let fastify;
return {
fastifyInstance: async () => {
if (!fastify) {
console.log("Called")
fastify = server();
await fastify.ready();
}
return fastify
}
}
})();
const { fastifyInstance } = getFastifyInstance
module.exports = fastifyInstance
Now wherever I am importing the code in a different file, the console prints "Called" each time it's imported in a new file, but shouldn't that be only once if singleton pattern was correctly implemented. Any idea what am I doing wrong?

Refactoring probot event functions into seperate file causes error: TypeError: handler is not a function

I have the vanilla probot event function from the docs that comments on new issues:
const probotApp = app => {
app.on("issues.opened", async context => {
const params = context.issue({ body: "Hello World!" });
return context.github.issues.createComment(params);
});
}
This works fine.
I refactor the code into a separate file:
index.js
const { createComment } = require("./src/event/probot.event");
const probotApp = app => {
app.on("issues.opened", createComment);
}
probot.event.js
module.exports.createComment = async context => {
const params = context.issue({ body: "Hello World!" });
return context.github.issues.createComment(params);
};
But I receive this error:
ERROR (event): handler is not a function
TypeError: handler is not a function
at C:\Users\User\probot\node_modules\#octokit\webhooks\dist-node\index.js:103:14
at processTicksAndRejections (internal/process/task_queues.js:97:5)
at async Promise.all (index 0)
When I create a test as recommended in the docs with a fixture and mock the event webhook call with nock this works fine. But when I create a real issue on GitHub this error is thrown.
How can I refactor the code into a separate file without causing the error?

This was my mistake.
This is the whole probot.event.js file:
module.exports.createComment = async context => {
const params = context.issue({ body: "Hello World!" });
return context.github.issues.createComment(params);
};
module.exports = app => {
// some other event definitions
}
By defining module.exports = app I overwrote the previous module.export. The createComment function was therefore never exported.
Removing module.exports = app = { ... } fixed it!

How to connect to mongoDB and test for drop collection?

This is how I connect to a mongoDB using monk(). I'll store it in state.
Assume we want to drop some collections, we call dropDB.
db.js
var state = {
db: null
}
export function connection () {
if (state.db) return
state.db = monk('mongdb://localhost:27017/db')
return state.db
}
export async function dropDB () {
var db = state.db
if (!db) throw Error('Missing database connection')
const Users = db.get('users')
const Content = db.get('content')
await Users.remove({})
await Content.remove({})
}
I'm not quite sure if it is a good approach to use state variable. Maybe someone can comment on that or show an improvement.
Now I want to write a unit test for this function using JestJS:
db.test.js
import monk from 'monk'
import { connection, dropDB } from './db'
jest.mock('monk')
describe('dropDB()', () => {
test('should throw error if db connection is missing', async () => {
expect.assertions(1)
await expect(dropDB()).rejects.toEqual(Error('Missing database connection'))
})
})
This part is easy, but the next part gives me two problems:
How do I mock the remove() methods?
test('should call remove() methods', async () => {
connection() // should set `state.db`, but doesn't work
const remove = jest.fn(() => Promise.resolve({ n: 1, nRemoved: 1, ok: 1 }))
// How do I use this mocked remove()?
expect(remove).toHaveBeenCalledTimes(2)
})
And before that? How do I setup state.db?
Update
As explained by poke the global variable makes the problem. So I switched to a class:
db.js
export class Db {
constructor() {
this.connection = monk('mongdb://localhost:27017/db');
}
async dropDB() {
const Users = this.connection.get('users');
const Content = this.connection.get('content');
await Users.remove({});
await Content.remove({});
}
}
which results in this test file:
db.test.js
import { Db } from './db'
jest.mock('./db')
let db
let remove
describe('DB class', () => {
beforeAll(() => {
const remove = jest.fn(() => Promise.resolve({ n: 1, nRemoved: 1, ok: 1 }))
Db.mockImplementation(() => {
return { dropDB: () => {
// Define this.connection.get() and use remove as a result of it
} }
})
})
describe('dropDB()', () => {
test('should call remove method', () => {
db = new Db()
db.dropDB()
expect(remove).toHaveBeenCalledTimes(2)
})
})
})
How do I mock out any this elements? In this case I need to mock this.connection.get()

Having a global state is definitely the source of your problem here. I would suggest to look for a solution that does not involve global variables at all. As per Global Variables Are Bad, global variables cause tight coupling and make things difficult to test (as you have noticed yourself).
A better solution would be to either pass the database connection explicitly to the dropDB function, so it has the connection as an explicit dependency, or to introduce some stateful object that holds onto the connection and offers the dropDB as a method.
The first option would look like this:
export function openConnection() {
return monk('mongdb://localhost:27017/db');
}
export async function dropDB(connection) {
if (!connection) {
throw Error('Missing database connection');
}
const Users = connection.get('users');
const Content = connection.get('content');
await Users.remove({});
await Content.remove({});
}
This would also make it very easy to test dropDB as you can now just pass a mocked object for it directly.
The other option could look like this:
export class Connection() {
constructor() {
this.connection = monk('mongdb://localhost:27017/db');
}
async dropDB() {
const Users = this.connection.get('users');
const Content = this.connection.get('content');
await Users.remove({});
await Content.remove({});
}
}
A test for the first option could look like this:
test('should call remove() methods', async () => {
const usersRemove = jest.fn().mockReturnValue(Promise.resolve(null));
const contentRemove = jest.fn().mockReturnValue(Promise.resolve(null));
const dbMock = {
get(type) {
if (type === 'users') {
return { remove: usersRemove };
}
else if (type === 'content') {
return { remove: contentRemove };
}
}
};
await dropDB(dbMock);
expect(usersRemove).toHaveBeenCalledTimes(1);
expect(contentRemove).toHaveBeenCalledTimes(1);
});
Basically, the dropDB function expects an object that has a get method which when called returns an object that has a remove method. So you just need to pass something that looks like that, so the function can call those remove methods.
For the class, this is a bit more complicated since the constructor has a dependency on the monk module. One way would be to make that dependency explicit again (just like in the first solution), and pass monk or some other factory there. But we can also use Jest’s manual mocks to simply mock the whole monk module.
Note that we do not want to mock the module containing our Connection type. We want to test that, so we need it in its un-mocked state.
To mock monk, we need to create a mock module of it at __mocks__/monk.js. The manual points out that this __mocks__ folder should be adjacent to the node_modules folder.
In that file, we simply export our custom monk function. This is pretty much the same we already used in the first example, since we only care about getting those remove methods in place:
export default function mockedMonk (url) {
return {
get(type) {
if (type === 'users') {
return { remove: mockedMonk.usersRemove };
}
else if (type === 'content') {
return { remove: mockedMonk.contentRemove };
}
}
};
};
Note that this refers to the functions as mockedMonk.usersRemove and mockedMonk.contentRemove. We’ll use this in the test to configure those function explicitly during the test execution.
Now, in the test function, we need to call jest.mock('monk') to enable Jest to mock the monk module with our mocked module. Then, we can just import it too and set our functions within the test. Basically, just like above:
import { Connection } from './db';
import monk from 'monk';
// enable mock
jest.mock('./monk');
test('should call remove() methods', async () => {
monk.usersRemove = jest.fn().mockReturnValue(Promise.resolve(null));
monk.contentRemove = jest.fn().mockReturnValue(Promise.resolve(null));
const connection = new Connection();
await connection.dropDB();
expect(monk.usersRemove).toHaveBeenCalledTimes(1);
expect(monk.contentRemove).toHaveBeenCalledTimes(1);
});