I have an app which tallies the number of visits to the url. The tallying is done in Redis. I'm using redis-mock which simulates commands like INCR in memory.
The following test visits the page 3 times and expects the response object to report current as 3:
let app = require('./app');
const supertest = require("supertest");
jest.mock('redis', () => jest.requireActual('redis-mock'));
/* Preceeded by the exact same test */
it('should report incremented value on multiple requests', (done) => {
const COUNT = 3;
const testRequest = function (cb) { supertest(app).get('/test').expect(200, cb) };
async.series([
testRequest,
testRequest,
testRequest
], (err, results) => {
if (err) console.error(err);
const lastResponse = _.last(results).body;
expect(
lastResponse.current
).toBe(COUNT);
done();
});
});
The issue is that if I keep reusing app, the internal "redis" mock will continue getting incremented between tests.
I can side-step this a bit by doing this:
beforeEach(() => {
app = require('./app');
jest.resetAllMocks();
jest.resetModules();
});
Overwriting app seems to do the trick but isn't there a way to clean-up the "internal" mocked module somehow between tests?
My guess is that somehow the '/test' endpoint gets invoked in some other tests in the suite, you could try to run specific parts of your suite using .only or even trying to run the entire suite serially.
To answer the original questions the entire suite must be isolated and consistent either if you are running a specific test case scenario or if you are trying to run the entire suite, thus you need to clear up any leftovers that they could actually affect the results.
So you can actually use the .beforeEach or the .beforeAll methods, provided by Jest in order to "mock" Redis and the .afterAll method for clearance.
A dummy implementation would look like this:
import redis from "redis";
import redis_mock from "redis-mock";
import request from "supertest";
jest.mock("redis", () => jest.requireActual("redis-mock"));
// Client to be used for manually resetting the mocked redis database
const redisClient = redis.createClient();
// Sometimes order matters, since we want to setup the mock
// and boot the app afterwards
import app from "./app";
const COUNT = 3;
const testRequest = () => supertest(app).get("/test");
describe("testing", () => {
afterAll((done) => {
// Reset the mock after the tests are done
jest.clearAllMocks();
// You can also flush the mocked database here if neeeded and close the client
redisClient.flushall(done);
// Alternatively, you can also delete the key as
redisClient.del("test", done);
redisClient.quit(done);
});
it("dummy test to run", () => {
expect(true).toBe(true);
});
it("the actual test", async () => {
let last;
// Run the requests in serial
for (let i = 0; i < COUNT - 1; i++) {
last = await testRequest();
}
// assert the last one
expect(last.status).toBe(200);
expect(last.body.current).toBe(COUNT);
});
});
Related
I want to test a node API using Jest. I am testing the routes and websockets. Testing the routes was no problem. I simply started the server using the setupFile option.
To test the websockets I wanted to pass the io object to the tests. This is not possible through the setupFile since the tests are running in their own context. Thus I changed to the testEnvironment option. My testEnvironment file is the following
const NodeEnvironment = require('jest-environment-node');
class CustomEnvironment extends NodeEnvironment {
constructor(config, context) {
super(config, context);
this.setupServer();
}
async setup() {
await super.setup();
console.log('Setup Test Environment.');
this.global.io = this.io;
this.global.baseUrl = 'http://localhost:' + this.port;
}
async teardown() {
await super.teardown();
console.log('Teardown Test Environment.');
}
getVmContext() {
return super.getVmContext();
}
setupServer() {
// Code for starting the server and attaching the io object
this.port = portConfig.http;
this.io = io;
}
}
module.exports = CustomEnvironment;
This works and the io object is passed to the test. I have multiple test files for different parts of the API. Running those with the setupFile was no problem but now Jest is only able to run one file. All following test suites are failing with the following message
● Test suite failed to run
TypeError: Cannot add property next, object is not extensible
at Function.handle (node_modules/express/lib/router/index.js:160:12)
at Function.handle (node_modules/express/lib/application.js:174:10)
at new app (node_modules/express/lib/express.js:39:9)
I am not able to find any documentation on that error. I tried disabling some of the test files but it always fails after the first one, no matter which one it is.
The structure of the test files is the following if relevant:
const axios = require('axios');
describe('Test MODULE routes', () => {
const baseUrl = global.baseUrl;
const io = global.io;
const models = require('../../../models'); // sequelize models which are used in tests
describe('HTTP METHOD + ROUTE', () => {
test('ROUTE DESCRIPTION', async () => {
const response = await axios({
method: 'get',
url: baseUrl + 'ROUTE'
});
expect(response.status).toBe(200);
});
});
// different routes
});
I fixed the error. It had nothing to do with jest but with an module.exports invocation in the server setup which overwrote the export of the CustomEnvironment with an express server.
I have an integration test where I make actual DB calls to the MongoDB database. But in order to test whether the transaction is expired or not, I need to mock the DB for that particular test. There are many reasons for me to make the actual DB call, I'm mentioning the state just for the sake of this example.
Jest has jest.doMock function but that is helpful only when I wanted to import the function within the test but in my case, It's the DB function which I wanted to mock for that particular test when is getting called inside the express middleware.
There is another option to mock the entire ../db module but that will complicate the tests a lot in my actual project. It would be very easy for me if I can mock the DB call for a specific test and for rest all the tests it should make the real DB calls.
Is there a way to do it in Jest?
// a.ts
import express from "express"
import db from "../db";
const app = express()
app.get("/api/deduct-balance/:txn_id", (req, res) => {
const txn = await db.findById(txn_id)
// return error message if txn expired
if (txn.exipre_at <= new Date()) {
return res.status(401).json({ error: "txn expired" });
}
// otherwise update the txn state
txn.state = "DEDUCTED";
await txn.save()
return res.status(200).json();
});
// a.test.ts
import db from "../db";
describe("mixed tests", () => {
test("should make REAL db calls", async () => {
await axios.get("/api/deduct-balance/123")
const txn = await db.findById("123");
expect(txn.state).toBe("DEDUCTED");
});
test("should use MOCKED value", async () => {
// need a way to mock the DB call so that I can return an expired transaction
// when I hit the API
const { data } = await axios.get("/api/deduct-balance/123")
expect(data).toBe({
error: {
message: "txn expired"
}
});
});
})
Integration tests are overkill for this scenario. Simple unit tests would suffice. They are fast to execute, test exactly one thing and you should have lots of them.
Because you're defining the handler as an anonymous function it's hard to unit test by default. So the first action is to make it easier to test by extracting it.
// deduct-balance-handlers.ts
export const deductBalanceByTransaction = async (req, res) => {
const txn = await db.findById(txn_id)
// return error message if txn expired
if (txn.exipre_at <= new Date()) {
return res.status(401).json({ error: "txn expired" });
}
// otherwise update the txn state
txn.state = "DEDUCTED";
await txn.save()
return res.status(200).json();
}
It will also makes the app configuration more clean.
// a.ts
import express from "express"
import db from "../db";
import { deductBalanceByTransaction } from './deduct-balance-handlers';
const app = express()
app.get("/api/deduct-balance/:txn_id", deductBalanceByTransaction);
Now it's easy to reuse the handler in your test without relying on the web framework or database.
// a.test.ts
import db from "../db";
import { deductBalanceByTransaction } from './deduct-balance-handlers';
jest.mock('../db');
describe("deduct-balance", () => {
test("Expired transaction should respond with 401 status", async () => {
const response = mockResponse();
deductBalanceByTransaction(request, response);
expect(response.status).toBe(401);
});
})
For simplicity's sake I left the part of creating a mock response and mocking the module out of the code. More can be learned about mocking here: https://jestjs.io/docs/en/manual-mocks
I am writing a typeScript program which hits an external API. In the process of writing tests for this program, I have been unable to correctly mock-out the dependency on the external API in a way that allows me to inspect the values passed to the API itself.
A simplified version of my code that hits the API is as follows:
const api = require("api-name")();
export class DataManager {
setup_api = async () => {
const email = "email#website.ext";
const password = "password";
try {
return api.login(email, password);
} catch (err) {
throw new Error("Failure to log in: " + err);
}
};
My test logic is as follows:
jest.mock("api-name", () => () => {
return {
login: jest.fn().mockImplementation(() => {
return "200 - OK. Log in successful.";
}),
};
});
import { DataManager } from "../../core/dataManager";
const api = require("api-name")();
describe("DataManager.setup_api", () => {
it("should login to API with correct parameters", async () => {
//Arrange
let manager: DataManager = new DataManager();
//Act
const result = await manager.setup_api();
//Assert
expect(result).toEqual("200 - OK. Log in successful.");
expect(api.login).toHaveBeenCalledTimes(1);
});
});
What I find perplexing is that the test assertion which fails is only expect(api.login).toHaveBeenCalledTimes(1). Which means the API is being mocked, but I don't have access to the original mock. I think this is because the opening line of my test logic is replacing login with a NEW jest.fn() when called. Whether or not that's true, I don't know how to prevent it or to get access to the mock function-which I want to do because I am more concerned with the function being called with the correct values than it returning something specific.
I think my difficulty in mocking this library has to do with the way it's imported: const api = require("api-name")(); where I have to include an opening and closing parenthesis after the require statement. But I don't entirely know what that means, or what the implications of it are re:testing.
I came across an answer in this issue thread for ts-jest. Apparently, ts-jest does NOT "hoist" variables which follow the naming pattern mock*, as regular jest does. As a result, when you try to instantiate a named mock variable before using the factory parameter for jest.mock(), you get an error that you cannot access the mock variable before initialization.
Per the previously mentioned thread, the jest.doMock() method works in the same way as jest.mock(), save for the fact that it is not "hoisted" to the top of the file. Thus, you can create variables prior to mocking out the library.
Thus, a working solution is as follows:
const mockLogin = jest.fn().mockImplementation(() => {
return "Mock Login Method Called";
});
jest.doMock("api-name", () => () => {
return {
login: mockLogin,
};
});
import { DataManager } from "../../core/dataManager";
describe("DataManager.setup_api", () => {
it("should login to API with correct parameters", async () => {
//Arrange
let manager: DataManager = new DataManager();
//Act
const result = await manager.setup_api();
//Assert
expect(result).toEqual("Mock Login Method Called");
expect(mockLogin).toHaveBeenCalledWith("email#website.ext", "password");
});
});
Again, this is really only relevant when using ts-jest, as using babel to transform your jest typescript tests WILL support the correct hoisting behavior. This is subject to change in the future, with updates to ts-jest, but the jest.doMock() workaround seems good enough for the time being.
I'm making a simple API with Express and I'm trying to add tests with Jest but when I try to run the tests it displays the next error:
ReferenceError: You are trying to `import` a file after the Jest environment has been torn down.
at BufferList.Readable (node_modules/readable-stream/lib/_stream_readable.js:179:22)
at BufferList.Duplex (node_modules/readable-stream/lib/_stream_duplex.js:67:12)
at new BufferList (node_modules/bl/bl.js:33:16)
at new MessageStream (node_modules/mongodb/lib/cmap/message_stream.js:35:21)
at new Connection (node_modules/mongodb/lib/cmap/connection.js:52:28)
/home/jonathangomz/Documents/Node/Express/Devotionals/node_modules/readable-stream/lib/_stream_readable.js:111
var isDuplex = stream instanceof Duplex;
^
TypeError: Right-hand side of 'instanceof' is not callable
I'm not sure to trust the result if right after jest break (or something like that):
My test is:
const app = require("../app");
const request = require("supertest");
describe("Testing root router", () => {
test("Should test that true === true", async () => {
jest.useFakeTimers();
const response = await request(app).get("/");
expect(response.status).toBe(200);
});
});
My jest configuration on package.json:
"jest": {
"testEnvironment": "node",
"coveragePathIgnorePatterns": [
"/node_modules/"
]
}
Notes:
I read about jest.useFakeTimers() but It's not working and I'm not sure if I'm using in the wrong way. I also tried adding it to the beforeEach method but nothing.
In my case, I had to add the package to transformIgnorePatterns in the jest config.
Add jest.useFakeTimers('modern') before the asynchronous call. Add jest.runAllTimers() after the asynchronous call. This will fast-forward timers for you.
const app = require("../app")
const request = require("supertest")
describe("Testing root router", () => {
test("Should test that true === true", async () => {
//Before asynchronous call
jest.useFakeTimers("modern")
const response = await request(app).get("/")
//After asynchronous call
jest.runAllTimers()
expect(response.status).toBe(200)
})
})
Try adding --testTimeout=10000 flag when calling jest, it works for me.
Information based on Testing NodeJs/Express API with Jest and Supertest
--testTimeout flag - This increases the default timeout of Jest which is 5000ms. This is important since the test runner needs to refresh the database before running the test
By adding jest.useFakeTimers() just after all your import.
What about making your test async ?
const app = require("../app");
const request = require("supertest");
describe("Testing root router",async () => {
test("Should test that true === true", async () => {
jest.useFakeTimers();
const response = await request(app).get("/");
expect(response.status).toBe(200);
});
});
We are trying to stub out an authentication middleware in an express app in some but not all of our tests, and we are having trouble making stubbing work for us.
Our mocha test looks something like this:
describe('primaryDeal routes unit test', () => {
describe('Authentication allows for data fetching', () => {
let app;
let getPrimaryDealData;
let queryParams;
let isAuthenticated;
let count = 0;
beforeEach(() => {
// console.log(isAuthenticated);
if (count === 0) {
isAuthenticated = sinon.stub(authCheck, 'isAuthenticated');
isAuthenticated.callsArg(2);
}
app = require('../../lib/index.js');
});
afterEach(() => {
if (count === 0) {
isAuthenticated.restore();
}
app.close();
count++;
});
it(('should send an API request, validate input and return 200 response'), () => {
return chai.request(app)
.get('/api/contracts/')
.then((res) => {
expect(res).to.have.status(200);
});
});
it(('should respond with forbidden'), () => {
app = require('../../lib/index.js');
return chai.request(app)
.get('/api/contracts/')
.catch((res, err) => {
expect(res).to.have.status(403);
});
});
});
});
Our stub works as intended for the first it, but the stub appears to not be restored for the second it and our authentication middleware is not being run. Both tests work if the other is commented out.
We've tried separating these blocks in different files, and in different describe blocks, we've also tried switching the order of the it blocks, and we've tried giving both chai.request(app) separate servers but we are at a loss.
Why could it be that our second it statement isn't calling our Auth middleware?
I recommend you to use sandbox. It's more elegant to use. No need to restore stubs individually. Here is an sample:
let sandbox;
beforeEach(() => {
sandbox = sinon.sandbox.create();
isAuthenticated = sandbox.stub(authCheck, 'isAuthenticated');
});
afterEach(() => {
sandbox.restore();
});
Also, could you try to add replace
app = require('../../lib/index.js');
to
delete require.cache[require.resolve('../../lib/index.js')]
app = require('../../lib/index.js');
Another thought, maybe you need to use reset not restore in this particular case?
P.S.
It's also good to see index.js source as well
I had the same issue and tried this solution without success. However the delete require.cache[require.resolve('../../lib/index.js')] gave me an idea. I was able to use decache instead of delete require. This resolved the problem for me.
const decache = require('decache');
decache('../../lib/index.js');