small README changes, minor code restyling

.simplecov

@@ -1,3 +1,6 @@
+# encoding: utf-8
+# frozen_string_literal: true
+
 SimpleCov.start do
   if ENV['RUN_CODECOV'] == 'true'
     require 'codecov'

Gemfile

@@ -1,4 +1,7 @@
-source "https://rubygems.org"
+# encoding: utf-8
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
 
 # gemspec
 

README.md

@@ -3,13 +3,13 @@
 [![Gem Version](https://img.shields.io/gem/v/pagy.svg?label=pagy&colorA=99004d&colorB=cc0066)](https://rubygems.org/gems/pagy)
 ![ruby](https://img.shields.io/badge/ruby-1.9+-ruby.svg?colorA=99004d&colorB=cc0066)
 ![jruby](https://img.shields.io/badge/jruby-1.7+-jruby.svg?colorA=99004d&colorB=cc0066)
-[![CodeCov](https://img.shields.io/codecov/c/github/ddnexus/pagy.svg?colorA=1f7a1f&colorB=2aa22a)](https://codecov.io/gh/ddnexus/pagy)
 [![Build Status](https://img.shields.io/travis/ddnexus/pagy/master.svg?colorA=1f7a1f&colorB=2aa22a)](https://travis-ci.org/ddnexus/pagy/branches)
+[![CodeCov](https://img.shields.io/codecov/c/github/ddnexus/pagy.svg?colorA=1f7a1f&colorB=2aa22a)](https://codecov.io/gh/ddnexus/pagy)
 [![MIT license](https://img.shields.io/badge/license-MIT-mit.svg?colorA=1f7a1f&colorB=2aa22a)](http://opensource.org/licenses/MIT)
+ [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/4329/badge)](https://bestpractices.coreinfrastructure.org/projects/4329)
 ![Commits](https://img.shields.io/github/commit-activity/y/ddnexus/pagy.svg?label=commits&colorA=004d99&colorB=0073e6)
 ![Downloads](https://img.shields.io/gem/dt/pagy.svg?colorA=004d99&colorB=0073e6)
 [![Chat](http://img.shields.io/badge/gitter-ruby--pagy-purple.svg?colorA=800080&colorB=b300b3)](https://gitter.im/ruby-pagy/Lobby)
- [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/4329/badge)](https://bestpractices.coreinfrastructure.org/projects/4329)
 
 Pagy is the ultimate pagination gem that outperforms the others in each and every benchmark and comparison.
 
@@ -212,6 +212,8 @@ Pagy follows the [Semantic Versioning 2.0.0](https://semver.org/). Please, check
 
 Pull Requests are welcome!
 
+Setting up a development environment for Pagy is very simple if you use the [docker environment](https://github.com/ddnexus/pagy/tree/pagy3/pagy3-on-docker).
+
 Before spending time creating a (potentially complex) Pull Request, you can [Confirm on Gitter](https://gitter.im/ruby-pagy/Lobby) whether your proposed changes are going to be useful for most users.
 
 If you Create A Pull Request, please ensure that the "All checks have passed" indicator gets green light on the Pull Request page. That means that the tests passed and Codecov and Rubocop are happy.

pagy.gemspec

@@ -1,3 +1,6 @@
+# encoding: utf-8
+# frozen_string_literal: true
+
 lib = File.expand_path('../lib', __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 require 'pagy'

pagy3-on-docker/README.md

@@ -32,22 +32,22 @@ You can also specify a few other variables used in the `docker-compose.yml` file
 If you already set the variables:
 
 ```sh
-cd pagy-on-docker
+cd pagy3-on-docker
 docker-compose build pagy pagy-jekyll
 ```
 
 or just set them with the command. For example:
 
 ```sh
-cd pagy-on-docker
+cd pagy3-on-docker
 GROUP=$(id -gn) UID=$(id -u) GID=$(id -g) docker-compose build pagy pagy-jekyll
 ```
 
 You need to run this only once, when you build the images. After that you just run th containers (see below).
 
 ## Use it
 
-Run the containers from the docker dir:
+Run the containers from the pagy3-on-docker dir:
 
 ```sh
 docker-compose up
@@ -59,6 +59,8 @@ Then you can run `irb -I lib -r pagy` from the container in order to have `pagy`
 
 Run all the tests by simply running `rake` without arguments.
 
+Notice: The rake taks is needed because certain tests must run in an isolated ruby process. For example, certain extras override the core pagy methods and we need to test how pagy works with or without the extra, or with many extras at the same time. You can get the full list of of all the test tasks (and test files that each task run) with `rake -D test_*`
+
 Check the coverage at `http://0.0.0.0:63342/pagy/coverage`
 
 The `pagy-jekyll` service runs the jekyll server so you can edit the docs files from the local `pagy` dir and have a real-time preview of your changes at `http://localhost:4000`. You don't even need to reload the page in the browser to see the change you do in the `*.md` page file.