Mocking API calls with Detox and Nock - react-native

I'm trying to mock API calls from Detox tests and nothing seems to be working. Nock in theory would do exactly what I want but there when I run my tests with nock debugging it isn't seeing any of the requests being made from my app. I'm using axios to make requests and I've tried setting the adapter on my axios instance to the http adapter.
Any suggestions on how to get nock working with Detox or if there is another mocking library you have had success with is appreciated, thanks!

What I ended up doing was leveraging the mocking specified in Detox docs (a separate *.e2e.js file hitting a different endpoint during tests). You define these special files that only run during e2e, I've set mine up to only hit localhost:9091 -- I then run an Express server on that port serving the endpoints I need.
Maybe an ugly way to do it, would love suggestions!
My mock file:
// src/helpers/axios.e2e.js
import axios from 'axios';
const instance = axios.create({
baseURL: `http://localhost:9091/api`,
});
export default instance;
Here's how I am running an express server during tests:
// e2e/mytest.e2e.js
const express = require('express');
let server;
beforeAll(async () => {
const app = express();
app.post('/api/users/register/', (req, res) => {
res.status(400)
res.send({"email": ["Test error: Email is required!"]})
})
await new Promise(function(resolve) {
server = app.listen(9091, "127.0.0.1", function() {
console.log(` Running server on '${JSON.stringify(server.address())}'...`);
resolve();
});
});
})
afterAll(() => {
server.close()
})

Related

Do we face any issues with creating apollo server and converting it to express server using apollo/server npm package?

pls check the below code,
// npm install #apollo/server express graphql cors body-parser
import { ApolloServer } from '#apollo/server';
import { expressMiddleware } from '#apollo/server/express4';
import { ApolloServerPluginDrainHttpServer } from '#apollo/server/plugin/drainHttpServer';
import express from 'express';
import http from 'http';
import cors from 'cors';
import bodyParser from 'body-parser';
import { typeDefs, resolvers } from './schema';
// Required logic for integrating with Express
const app = express();
// Our httpServer handles incoming requests to our Express app.
// Below, we tell Apollo Server to "drain" this httpServer,
// enabling our servers to shut down gracefully.
const httpServer = http.createServer(app);
// Same ApolloServer initialization as before, plus the drain plugin
// for our httpServer.
const server = new ApolloServer({
typeDefs,
resolvers,
plugins: [ApolloServerPluginDrainHttpServer({ httpServer })],
});
// Ensure we wait for our server to start
await server.start();
// Set up our Express middleware to handle CORS, body parsing,
// and our expressMiddleware function.
app.use(
'/',
cors(),
bodyParser.json(),
// expressMiddleware accepts the same arguments:
// an Apollo Server instance and optional configuration options
expressMiddleware(server, {
context: async ({ req }) => ({ token: req.headers.token }),
}),
);
// Modified server startup
await new Promise((resolve) => httpServer.listen({ port: 4000 }, resolve));
console.log(`🚀 Server ready at http://localhost:4000/`);
The code is from official documentation of apollo server, My question is, here we are first creating an apollo server and converting it to express server using expressMiddleware(server),
Will there be any issues with this conversion ?
Will we face any lack of control over the converted express server ?
My question is, here we are first creating an apollo server and converting it to express server using expressMiddleware(server),
That's not what you're doing at all.
You created an express server (const app = express()).
You created a separate http server from that app.
You created a running executable GraphQL Server.
You created an express middleware ((req, res, next) => void) that generates a context of { token?: string }, parses the body of your request into a GraphQL payload and then executes against the GraphQL Server with that context and with that payload.
You then added that express middleware to a route you created at "/", along with other middleware you attached before it.
You started the httpServer you created in #2
Will there be any issues with this conversion ?
Will we face any lack of control over the converted express server ?
This is no conversion, as mentioned. Hopefully you now understand that.
You created all of those things. Your express app is a variable called app. Do whatever you want with it. Your http server is a variable called httpServer. Do whatever you want with it.

How do I mock server-side API calls in a Nextjs app?

I'm trying to figure out how to mock calls to the auth0 authentication backend when testing a next js app with React Testing Library. I'm using auth0/nextjs-auth0 to handle authentication. My intention is to use MSW to provide mocks for all API calls.
I followed this example in the nextjs docs next.js/examples/with-msw to set up mocks for both client and server API calls. All API calls generated by the auth0/nextjs-auth0 package ( /api/auth/login , /api/auth/callback , /api/auth/logout and /api/auth/me) received mock responses.
A mock response for /api/auth/me is shown below
import { rest } from 'msw';
export const handlers = [
// /api/auth/me
rest.get(/.*\/api\/auth\/me$/, (req, res, ctx) => {
return res(
ctx.status(200),
ctx.json({
user: { name: 'test', email: 'email#domain.com' },
}),
);
}),
];
The example setup works fine when I run the app in my browser. But when I run my test the mocks are not getting picked up.
An example test block looks like this
import React from 'react';
import {render , screen } from '#testing-library/react';
import Home from 'pages/index';
import App from 'pages/_app';
describe('Home', () => {
it('should render the loading screen', async () => {
render(<App Component={Home} />);
const loader = screen.getByTestId('loading-screen');
expect(loader).toBeInTheDocument();
});
});
I render the page inside the App component like this <App Component={Home} /> so that I will have access to the various contexts wrapping the pages.
I have spent about 2 days on this trying out various configurations and I still don't know what I might be doing wrong. Any and every help is appreciated.
This is probably resolved already for the author, but since I ran into the same issue and could not find useful documentation, this is how I solved it for end to end tests:
Overriding/configuring the API host.
The plan is to have the test runner start next.js as custom server and then having it respond to both the next.js, as API routes.
A requirements for this to work is to be able to specify the backend (host) the API is calling (via environment variables). Howerver, access to environment variables in Next.js is limited, I made this work using the publicRuntimeConfig setting in next.config.mjs. Within that file you can use runtime environment variables which then bind to the publicRuntimeConfig section of the configuration object.
/** #type {import('next').NextConfig} */
const nextConfig = {
(...)
publicRuntimeConfig: {
API_BASE_URL: process.env.API_BASE_URL,
API_BASE_PATH: process.env.API_BASE_PATH,
},
(...)
};
export default nextConfig;
Everywhere I reference the API, I use the publicRuntimeConfig to obtain these values, which gives me control over what exactly the (backend) is calling.
Allowing to control the hostname of the API at runtime allows me to change it to the local machines host and then intercept, and respond to the call with a fixture.
Configuring Playwright as the test runner.
My e2e test stack is based on Playwright, which has a playwright.config.ts file:
import type { PlaywrightTestConfig } from '#playwright/test';
const config: PlaywrightTestConfig = {
globalSetup: './playwright.setup.js',
testMatch: /.*\.e2e\.ts/,
};
export default config;
This calls another file playwright.setup.js which configures the actual tests and backend API mocks:
import {createServer} from 'http';
import {parse} from 'url';
import next from 'next';
import EndpointFixture from "./fixtures/endpoint.json";
// Config
const dev = process.env.NODE_ENV !== 'production';
const baseUrl = process?.env?.API_BASE_URL || 'localhost:3000';
// Context
const hostname = String(baseUrl.split(/:(?=\d)/)[0]).replace(/.+:\/\//, '');
const port = baseUrl.split(/:(?=\d)/)[1];
const app = next({dev, hostname, port});
const handle = app.getRequestHandler();
// Setup
export default async function playwrightSetup() {
const server = await createServer(async (request, response) => {
// Mock for a specific endpoint, responds with a fixture.
if(request.url.includes(`path/to/api/endpoint/${EndpointFixture[0].slug}`)) {
response.write(JSON.stringify(EndpointFixture[0]));
response.end();
return;
}
// Fallback for pai, notifies about missing mock.
else if(request.url.includes('path/to/api/')) {
console.log('(Backend) mock not implementeded', request.url);
return;
}
// Regular Next.js behaviour.
const parsedUrl = parse(request.url, true);
await handle(request, response, parsedUrl);
});
// Start listening on the configured port.
server.listen(port, (error) => {
console.error(error);
});
// Inject the hostname and port into the applications publicRuntimeConfig.
process.env.API_BASE_URL = `http://${hostname}:${port}`;
await app.prepare();
}
Using this kind of setup, the test runner should start a server which responds to both the routes defined by/in Next.js as well as the routes intentionally mocked (for the backend) allowing you to specify a fixture to respond with.
Final notes
Using the publicRuntimeConfig in combination with a custom Next.js servers allows you to have a relatively large amount of control about the calls that are being made on de backend, however, it does not necessarily intercept calls from the frontend, the existing frontend mocks might stil be necessary.

Supertest and jest: cannot close express connection

I am using jest and supertest to raise instance of express and run tests on it.
I faced with the problem of busy port that cannot still solve.
In my test I do the next:
import supertest from 'supertest';
const agent = supertest(app);
Then I go requests with agent and everything works fine.
Until I am running another test.
In app.js I have:
var app = express();
app.post('/auth/changePassword',VerifyToken, auth.changePassword);
app.listen(4001, function () {
console.log('Server is running');
});
So first spec runs perfect. But second tries to listen to the port that is already in use.
I really do not know how to close the connection here.
I tried app.close() but got error that such method. This is clear, that I have to assign
server = app.listen(4001, function () {
console.log('Server is running');
});
server.close();
But do not know how can I do that.
I also tried to preset agent in jest.setup and assign it to global variable
import app from "../../server/app";
import supertest from 'supertest';
const agent = supertest(app);
global.agent = agent;
But situation is the same, first test passed, second tries to raise express on the same port.
Supertest is able to start and stop your app for you - you should never need to explicitly kill the express server during the tests (even when running in parallel)
The problem is that in app.js your server is actually started - this means that when the app tests are run your server is started every time app.js is read (or once per test case)
You can remedy this by splitting the server start logic into a seperate file, so that importing app.js doesn't start the app (rather returns an express server instance) The pattern I normally use for this is:
// app.js
import express from 'express'
export const app = express();
app.get("/example", (req,res) => {
return res.status(200).json({data: "running"})
})
// server.js
import app from "./app"
app.listen(3000, () => console.log("listening on 3000"));
// app.spec.js
import app from "./app"
import request from "supertest"
it("should be running", async () => {
const result = await request(app).get("/example");
expect(result.body).toEqual({data: "running"});
});

Prevent supertest from running until express server has started

I have an node / express js app that was generated using the yoman full stack generator. I have swapped out mongo / mongoose for cloudant db (which is just a paid for version of couchdb). I have a written a wrapper for the Cloudant node.js library which handles cookie auth with my instance via an init() method wrapped in a promise. I have refactored my application to not start the express server until the connection to the db has been established as per snippet below taken from my app.js
myDb.init(config).then(function (db) {
logger.write(1001, '','Connection to Cloudant Established');
// Start server
server.listen(config.port, config.ip, function () {
logger.write(1001, "",'Express server listening on '+config.port+', in '+app.get('env')+' mode');
});
});
On my express routes I have introduced a new middleware which attaches the db object to the request for use across the middleware chain as per below. This gets the db connection object before setting the two collections to use.
exports.beforeAll = function (req, res, next) {
req.my = {};
// Adding my-db
req.my.db = {};
req.my.db.connection = myDb.getDbConnection();
req.my.db.orders = req.my.db.connection.use(dbOrders);
req.my.db.dbRefData = req.my.db.connection.use(dbRefData);
next();
};
This mechanism works when i manually drive my apis through POSTman as the express server won't start until after the promise from the db connection has been resolved. However when running my automated tests the first few tests are now always failing because the application has not finished initialising with the db before jasmine starts to run my tests against the APIs. I can see in my logs the requests on the coming through and myDb.getDbConnection(); in the middleware returning undefined. I am using supertest and node-jasmine to run my tests. For example
'use strict';
var app = require('../../app');
var request = require('supertest');
describe('GET /api/content', function () {
it('should respond with JSON object', function (done) {
request(app)
.get('/api/content')
.expect(200)
.expect('Content-Type', /json/)
.end(function (err, res) {
if (err) return done(err);
expect(res.body).toEqual(jasmine.any(Object));
done();
});
});
});
So, my question is how can I prevent supertest from making the requests until the server.listen() step has been completed as a result of the myDb.init() call being resolved? OR perhaps there is some kind of jasmine beforeAll that I can use to stop it running the describes until the promise has been resolved?
You could make you app return an EventEmitter which emits a "ready" event when it has completed its initialisation.
Then your test code, in a before clause, can wait until the "ready" event arrives from the app before proceeding with the tests.

React Router, pushState with an Express Server

quick question regarding using React-Router. I'm having trouble getting my server to handle pushState (if this is the correct term). Originally, I was using a module called connect-history-api-fallback, which was a middleware that enabled me to only server up static files form my dist directory. Visiting the client www.example.com obviously worked and I could navigate throughout the site, additionally, refreshing at any route like www.example.com/about - could also work.
However, I recently added one simple API endpoint on my Express server for the React app/client to ping. The problem now is that while I can get the initial page load to work (and thus the /api/news call to work, to fetch data from a remote service), I can no longer do a refresh on any other routes. For example, now going to www.example.com/about will result in a failed GET request for /about. How can I remediate this? Really appreciate the help! PS - not sure if it matters, but I'm considering implementing Server Side Rendering later on.
import express from 'express';
import historyApiFallback from 'connect-history-api-fallback';
import config from '../config';
import chalk from 'chalk';
import fetch from 'node-fetch';
import path from 'path';
const app = express();
// FIXME: Unsure whether or not this can be used.
// app.use(historyApiFallback({
// verbose : true
// }));
//// DEVELOPMENT MODE ONLY - USING EXPRESS + HMR ////
/* Enable webpack middleware for hot module reloading */
if (config.get('globals').__DEV__) {
const webpack = require('webpack');
const webpackConfig = require('../build/webpack/development_hot');
const compiler = webpack(webpackConfig);
app.use(require('./middleware/webpack-dev')({
compiler,
publicPath : webpackConfig.output.publicPath
}));
app.use(require('./middleware/webpack-hmr')({ compiler }));
}
//// PRODUCTION MODE ONLY - EXPRESS SERVER /////
if (config.get('globals').__PROD__) {
app.use(express.static(__dirname + '/dist'));
}
//// API ENDPOINTS FOR ALL ENV ////
app.get('/api/news', function (req, res) {
fetch('http://app-service:5000/news')
.then( response => response.json() )
.then( data => res.send(data) )
.catch( () => res.sendStatus(404) );
});
// Wildcard route set up to capture other requests (currently getting undexpected token '<' error in console)
app.get('*', function (req, res) {
res.sendFile(path.resolve(__dirname, '../dist', 'index.html'));
});
export default app;
Express works by implementing a series of middleware that you "plug in" in order via .use. The cool thing is your routes are also just middlware — so you can separate them out, have them before your history fallback, and then only requests that make it past your routes (e.g., didn't match any routes) will hit the fallback.
Try something like the following:
const app = express();
// ...
var routes = exprss.Router();
routes.get('/api/news', function (req, res) {
fetch('http://app-service:5000/news')
.then( response => response.json() )
.then( data => res.send(data) )
.catch( () => res.sendStatus(404) );
});
app.use(routes);
app.use(historyApiFallback({
verbose : true
}));