I would like to test code in a node project that uses async iteration without using babel.
Based on https://github.com/facebook/jest/issues/2485, I tried running jest using node --harmony_async_iteration ./node_modules/.bin/jest. However, I still see syntax errors in my module where async iteration syntax is used. The node command line option was ineffective, as if jest spawned a new process for the test runner, without using --harmony_async_iteration.
My async iteration source file is parsed without error when loaded by node (without jest) using --harmony_async_iteration.
Babel is an integral part of jest. It is not necessary to use babel to transpile your application for non-test use, but babel absolutely must be configured in order to allow async generators to work with jest.
Install the babel-plugin-transform-async-generator-functions:
npm install --save-dev babel-plugin-transform-async-generator-functions
or
yarn add --dev babel-plugin-transform-async-generator-functions
Activate the plugin by creating a .babelrc file (or add to the file):
{ "plugins": ["transform-async-generator-functions"] }
Now your jest tests should work with async generators.
Related
I followed this answer to make jest work with esm packages
node - using jest with esm package
But I get an error when I try to do jest.SpyOn because it said that jest is undefined.
I did some digging and notice that jest is present on my app.test.js file but not in the asserts.js
So I was wondering how can I get the jest variable on the assert file or can I import jest directly without relaying on injecting it like the default config
I'm using WebStorm and a newbie to it. when I use import/export statements, it gives me an error of
Unexpected token import
but if I try with require/module.exports it works fine.
N.B- I've configured language version as ES6 from Languages and Frameworks.
This is not WebStorm but Node.js that fails. While import is a part of ES6, native support for ES6 modules in Node.js is very limited and requires special setup - see https://nodejs.org/api/esm.html#esm_enabling. So, you have to compile your code with Babel first. Usually transpiling is a part of build process (using Gulp, Grunt, WebPack, etc.). Or, you can transpile your code on-the-fly by passing -r babel-register to Node.js. Of course, you need creating appropriate .babelrc and install the required modules (npm install --save-dev babel-cli babel-preset-env)
Can someone help me run a node.js file that has ES6 features? This is my current workflow:
Save change in file
npm run build --- builds file to my src/dist folder
cd into my dist directory
node
var file = require('./index.js')
file.someMethod()
Then when I make a change to my method, I need to repeat all the steps above again.
Does anyone know of a more efficient way to do this?
Thanks in advance!
You dont need anything if you are not using import/export. Just Install node 8.x and then run node my_file.js. Nodejs supports most of the es6 features out of the box.
If you want to use import/export then I would recommend to use typescript: https://www.typescriptlang.org/. It has compiler TS (statically typed ES6) to ES5.
Oh, and of course both babel and typescript have watcher modules (auto recompiling on file change).
It really depends on what npm run build actually does in your app. Does it run gulp/grunt? Webpack? Etc. If it's webpack there is a webpack-dev-server that you should look into.
If it's grunt or gulp then you have a custom build chain that you're working with. If all you need is to support es6 features without having to build the project then you could use something simple like babel-cli and run your file from outside the dist directory.
$ npm i -g babel-cli
$ babel-node
> var file = require('./index.js');
> file.someMethod()
By running babel-node you're running the normal node repl but with babel required. Es6 features should now be supported in the repl without needing to be compiled to es5.
You may also want to try simply updating to the latest version of node because node 8 has pretty extensive es6 support.
Jest creates this global called expect. How can I use that without using their test runner? i.e., what do I have to import/require?
The module is simply called expect
e.g.
import expect from 'expect'
expect(1 + 1).toBe(2)
You can see it in the Jest lerna repo and the individual package on npm
I wrote a very basic express.js app. Then tried to make it one .js file. Browserify compiled the whole thing to a one file. But browserify-compiled code didn't work. As far as I know, browserify just replaces require statements with module codes. Error is:
C:\Users\HP\n\express\app.js:27025
__proto__: http.IncomingMessage.prototype
^
TypeError: Cannot read property 'prototype' of undefined
at Object.__dirname.173.accepts (C:\Users\HP\n\express\app.js:27025:34)
at s (C:\Users\HP\n\express\app.js:1:316)
at C:\Users\HP\n\express\app.js:1:367
at Object.__dirname.170../application (C:\Users\HP\n\express\app.js:26823:11)
at s (C:\Users\HP\n\express\app.js:1:316)
at C:\Users\HP\n\express\app.js:1:367
at Object.__dirname.168../lib/express (C:\Users\HP\n\express\app.js:26154:18)
at s (C:\Users\HP\n\express\app.js:1:316)
at C:\Users\HP\n\express\app.js:1:367
at Object.__dirname.153.express (C:\Users\HP\n\express\app.js:24010:15)
Browserify is designed specifically to package code for a browser.
Node.js supports a number of modules that a browser doesn't which have to be emulated by builtins. These modules will be replaced by a browser-specific shim. Some only supply a subset of the Node API that makes sense to have in a browser.
So you are running an app that has converted all the Node.js modules to support running what it can in a browser, back in Node where the modules are available but are no longer being used.
Try rollup or you could possibly configure babel to work like you need
I had this very same issue but like you said the compile code should work on server side. I solved it from this link:
https://www.linkedin.com/pulse/bundling-nodemodules-your-nodejs-app-one-single-file-xuan-son-nguyen/
Use browserify for bundling and terser for minifying. Starting by installing them globally:
npm install -g browserify
npm install -g terser
Next, we have to add a build script to package.json
...
"scripts": {
...
"build": "browserify --node --ignore-missing index.js | terser > bundle.js"
}
...
Each time you want to promote to production, you have to make a new bundle:
npm run build
A new file called "bundle.js" will be created.
Let there be peace, and there was peace. Happy coding.