Today I Learned

A Hashrocket project

16 posts by andrewvogel @calllmehvogel

Fix Timeouts and Speed Up Jest on CI

If you have a large or complex test suite, running Jest on CI can make your build especially slow or cause timeouts. Luckily, Jest has an option cut out for this.

jest --runInBand

runInBand runs all tests serially inside the current process instead of creating a bunch workers. Using this option, we were able to trim suite time above 20mins down to less than 4 mins. 🏎️😎

Change Name of :id Param in Rails Resource Routing

You can change the name of the parameter used by rails resource routing by specifying the param option to the resource route.

For example, if we have a show endpoint:

resources :pages, only: :show

Running rake routes will return the pages#show url as:


We can change the id param to slug by doing:

resources :pages, only: :show, param: :slug

Then running rake routes will yield our new pages#show route as:


Generate Absolute File Path In Ruby

Pass a string to File.expand_path to generate the path to that file or directory. Relative paths will reference your current working directory, and paths prepended with ~ will use the owner’s home directory.

=> "/Users/avogel/My/Working/Directory/example.rb"

=> "/Users/avogel/example.rb"

Deleting Words in Vim

As a recent vim convert, I learn new commands everyday from my fellow rocketeers. Here’s some cool ones for deleting words:

  • Use dw to delete word. Cursor placement is important! If your cursor is not on the first character, it will only delete from your cursor to the end of the word.
  • Use diw to delete inside word. Deletes the entire word that your cursor resides in.
  • Use dt<char> to delete to character. Deletes from your cursor to the specified character.

Getting BetterErrors in Rails While Using Ngrok

By default, the BetterErrors gem only works for localhost. If you’re using ngrok to access your rails server and you want to have access to BetterErrors, you’ll need to whitelist the IP of the machine that ngrok is running on.

Add the following to development.rb:

# - or -
# Use an IP finding service to grab your public IP each time you start the server:
# (,, etc.)

Set the Domain or Host in Rails URL Helpers

You can explicitly set the domain with Rails URL Helpers:

=> ""

app.root_url(domain: '')
=> ""


If we include the protocol in our domain argument, this brings up an interesting gotcha. Check it out:

app.root_url(domain: '')
=> "http://www."


Thankfully, Rails gives us the host option. Host will use a Regex to remove the protocol from the argument:

app.root_url(host: '')
=> ""


Notice the output in the last example; our protocol was replaced removed and replaced with http. You can use the protocol argument to enforce your protocol on a given host:

app.root_url(host: '', protocol: 'https')
=> ""

Alias A Model Method Or Field in a GraphQL Type

If you need to override the name of a model method or field in a GraphQL type, you can use the property argument.

Let’s say we have a model called Message:

class Message < ApplicationRecord
  def bar

We can then make an alias to the bar method by specifying a property in our MessageType:

Types::MessageType = GraphQL::ObjectType.define do 
  field :foo, types.String, property: :bar