Rick Wong RickWong

Idiomatic React Testing Patterns

Testing React components seems simple at first. Then you need to test something that isn't a pure interaction and things seem to break down. These 4 patterns should help you write readable, flexible tests for the type of component you are testing.

Setup

I recommend doing all setup in the most functional way possible. If you can avoid it, don't set variables in a beforeEach. This will help ensure tests are isolated and make things a bit easier to reason about. I use a pattern that gives great defaults for each test example but allows every example to override props when needed:

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This article shows how to apply Node.js Stream and a bit of Reactive programming to a real(tm) problem. The article is intended to be highly practical and oriented for an intermediate reader. I intentionally omit some basic explanations. If you miss something try to check the API documentation or its retelling(e.g.: this one)

So, lets start from the problem description. We need to implement a simple web scraper which grabs all the data from some REST API, process the data somehow and inserts into our Database. For simplicity, I omit the details about the actual database and REST API(in real life it was the API of some travel fare aggregator website and a Pg database)

Consider we have two functions(code of the IO simulator functions and the other article code is here):

getAPI(n, count) // pseudo API ca

Usage

sed -E -f solver.sed input where input is a file containing the maze.

For best results, resize your terminal to match the height of the maze. To disable animations, delete the lines containing p.

Maze format

The solver assumes the following:

The maze only contains the characters # \nSE
Every line has the same number of characters
There is only one start (S) and end (E)

	var INIT = '@redux/INIT'

	function createStore (reducer, state, enhancer) {
	if (enhancer) return enhancer(createStore)(reducer, state)

	var subscribers = []

	dispatch({ type: INIT })

	return {

	/*<?php
	///public class PhpJava { public static void main(String[] args) { System.out.printf("/%s",
	//\u000A\u002F\u002A
	class PhpJava {
	static function main() {
	echo(//\u000A\u002A\u002F
	"Hello World!");
	}}
	//\u000A\u002F\u002A
	PhpJava::main();

	The question was asked why I (as a programmer who prefers dynamic languages) don't consider static types "worth it". Here
	is a short list of what I would need from a type system for it to be truely useful to me:

	1) Full type inference. I would really prefer to be able to write:

	(defn concat-names [person]
	(assoc person :full-name (str (:first-name person)
	(:second-name person))))

	And have the compiler know that whatever type required and produced from this function was acceptible as long as the

	import React from 'react'
	import { render } from 'react-dom'

	// with fiber, we'll be able to write components that update text deep
	// inside another string without wrapper dom, or rerendering the whole component

	// before
	class Lorem extends React.Component {
	state = {
	str: ''

	// Types:
	type Just<T> = { Just: T }
	type Nothing = {}
	type Maybe<T> = Just<T> \| Nothing

	type Left<L> = { Left: L }
	type Right<R> = { Right: R }
	type Either<L, R> = Left<L> \| Right<R>

	// For convenience:

	/*****************************************************************************
	* QuantCup 1: Price-Time Matching Engine
	*
	* Submitted by: voyager
	*
	* Design Overview:
	* In this implementation, the limit order book is represented using
	* a flat linear array (pricePoints), indexed by the numeric price value.
	* Each entry in this array corresponds to a specific price point and holds
	* an instance of struct pricePoint. This data structure maintains a list