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# frozen_string_literal: true

require "active_support/all"

def null_on_db?(table_name, col_name)
  db_structure = File.read("db/structure.sql")
  db_structure.match(/CREATE TABLE public.#{table_name} \((?<cols>.*?)\)/m) || {cols: ""} => { cols: attrs }
  attrs.match?(/#{col_name}.*NOT NULL/)
end

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Here are some of the things I've identified that can cause flaky tests.

Race conditions

A common type of race condition in tests is this: the test submits a form and then clicks a link on the subsequent page. BUT sometimes the page loads a little more slowly than at other times, and so the test driver clicks the link before the link actually shows up on the page. It's a race between the link showing up and the test trying to click the link. In the cases where the click "wins" the race, the test will fail because the link isn't available yet. Other kinds of race conditions exist too but that's a common case.

Leaked state

Let's imagine there's a test suite with just two tests in it, test A and test B. Both tests create a user in the database with the email address "[email protected]". But the difference between the two tests is that test A deletes the user at the end of the test, while test B leaves the user lying around in the database. If test A runs before test B then there's no problem because test A

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class LeaseLiability
  attr_reader :year, :fixed_payment, :annual_increase, :discount_rate, :initial_direct_cost,
              :cash_incentives
  attr_accessor :beginning_balance

  def initialize(
    year:,
    fixed_payment:,
    annual_increase:,
    discount_rate:,

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a = [1,2,3,4,5]
b = [2,4,5,9,8,7]
result = []
a.each do |ai|
  result << b.find { |bj| bj == ai }
end
return result

Orden a.length * b.length

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Problem

Models

class Post < ApplicationRecord
    has_many :comments
end

class User < ApplicationRecord
  has_many :comments
end

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Docker Cheat Sheet

docker

Create Dockerfile --> contiene el provisioning (todo lo que tiene que tener instalado) base image -> ruby:2.3.0 RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs

RUN mdkir /myapp WORKDIR /myapp

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class ResultWrapper
  attr_reader :value, :success?, :error_messages
  def failure?
    !success?
  end
end

class SomeController
  def create
    result = process(params[:id])

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Title

Development

• Creating gems
• Installing gems
• Private repos - Gemfury
• rbenv - manage installed ruby versions
• bundler - manage gems based on gemfile

Ruby

• Regexp

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require 'thread'

params_for_job = Queue.new
workers = []
def perform_task(params_for_job)
  while x = params_for_job.pop
    print x + "\n"
  end
  return x
end

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jest.mock('node-fetch');
import fetch, {Response} from 'node-fetch';

  it('can mock fetch body', () => {
    fetch.mockImplementation(() => {
      return new Promise((resolve, reject)=> { resolve(
        {
          json: () => { return new Promise((resolve, reject) => resolve({ name: 'value' })) }
        }
      )})