Kim Røen kimroen

This assert.asyncThrows custom assertion allows us to write tests against failing async code, usually as a result of a server error (4xx/5xx response).

test('If the index route errors, I see a message', async function(assert) {
  server.create('post');
  server.get('/posts/:id', { errors: ['The site is down'] }, 500); // force Mirage to error

  await assert.asyncThrows(() => {
    return visit('/posts/1');
 }, 'GET /posts/1 returned a 500');

Heroku Release Phase + Review Apps + Rails

This is a simplified, but fairly thorough, set of scripts and configuration to enable Heroku Release Phase for Rails apps. Further, this particular set up plays nicely with Heroku Review Apps in that the release phase script will:

Fail, loudly, if the DB does not yet exist.
Load the DB schema if the current schema version (as determined by bin/rails db:version) is 0.
Run DB migrations otherwise.

For a "normal" app that usually means it will run the DB migrations.

async/await is just the do-notation of the Promise monad

CertSimple just wrote a blog post arguing ES2017's async/await was the best thing to happen with JavaScript. I wholeheartedly agree.

In short, one of the (few?) good things about JavaScript used to be how well it handled asynchronous requests. This was mostly thanks to its Scheme-inherited implementation of functions and closures. That, though, was also one of its worst faults, because it led to the "callback hell", an seemingly unavoidable pattern that made highly asynchronous JS code almost unreadable. Many solutions attempted to solve that, but most failed. Promises almost did it, but failed too. Finally, async/await is here and, combined with Promises, it solves the problem for good. On this post, I'll explain why that is the case and trace a link between promises, async/await, the do-notation and monads.

First, let's illustrate the 3 styles by implementing

This document has moved!

It's now here, in The Programmer's Compendium. The content is the same as before, but being part of the compendium means that it's actively maintained.

	export default class StyleGroup {
	constructor(styles) {
	this.styles = styles;
	this.name = ''; // must set at runtime
	}
	}

	#!/bin/bash

	set -e

	CONTENTS=$(tesseract -c language_model_penalty_non_dict_word=0.8 --tessdata-dir /usr/local/share/tessdata/ "$1" stdout -l eng \| xml esc)

	hex=$((cat <<EOF
	<?xml version="1.0" encoding="UTF-8"?>
	<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
	<plist version="1.0">

	// tests/helpers/push-mirage-db-into-store.js
	import { registerAsyncHelper } from '@ember/test';
	import { run } from '@ember/runloop';

	let pushMirageDbIntoStore = function(server, store) {
	let tables = Object.keys(server.schema);

	tables.forEach(table => {
	if (server.schema[table].all) {
	let all = server.schema[table].all();

	const trackTime = timing => {
	const now = performance.now();
	if (!timing.startTime) timing.startTime = now;
	const elapsed = now - timing.startTime;
	const {duration} = timing;
	if (duration != null && duration <= elapsed) timing.startTime = null;
	return elapsed;
	};

	const delay = (callback, duration) => {

	I hear no princess in the night
	But Link hears all her whispers of defenestration
	He’s coming in, paraglider flight
	The sheikah slate reflects the past that guides him toward salvation
	Got stopped by an old man along the way
	Hoping to find some long forgotten tech or ancient memories
	He turned to me as if to say, “Hurry boy, she’s waiting there for you"

	It's gonna take a lot to clean up all that evil goo
	There's nothing in a hundred years or more that they could do

	:root {
	--ease-in-quad: cubic-bezier(.55, .085, .68, .53);
	--ease-in-cubic: cubic-bezier(.550, .055, .675, .19);
	--ease-in-quart: cubic-bezier(.895, .03, .685, .22);
	--ease-in-quint: cubic-bezier(.755, .05, .855, .06);
	--ease-in-expo: cubic-bezier(.95, .05, .795, .035);
	--ease-in-circ: cubic-bezier(.6, .04, .98, .335);

	--ease-out-quad: cubic-bezier(.25, .46, .45, .94);
	--ease-out-cubic: cubic-bezier(.215, .61, .355, 1);