Demonstrate alleged bug in the faraday gem, wherein streaming appears to be broken by persistence

.ruby-version

ruby-3.0.1

Gemfile

# frozen_string_literal: true

source "https://rubygems.org"

git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }

gem "faraday", "1.5.0"
gem "net-http-persistent", "4.0.1"

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    connection_pool (2.2.5)
    faraday (1.5.0)
      faraday-em_http (~> 1.0)
      faraday-em_synchrony (~> 1.0)
      faraday-excon (~> 1.1)
      faraday-httpclient (~> 1.0.1)
      faraday-net_http (~> 1.0)
      faraday-net_http_persistent (~> 1.1)
      faraday-patron (~> 1.0)
      multipart-post (>= 1.2, < 3)
      ruby2_keywords (>= 0.0.4)
    faraday-em_http (1.0.0)
    faraday-em_synchrony (1.0.0)
    faraday-excon (1.1.0)
    faraday-httpclient (1.0.1)
    faraday-net_http (1.0.1)
    faraday-net_http_persistent (1.1.0)
    faraday-patron (1.0.0)
    multipart-post (2.1.1)
    net-http-persistent (4.0.1)
      connection_pool (~> 2.2)
    ruby2_keywords (0.0.4)

PLATFORMS
  x86_64-linux

DEPENDENCIES
  faraday (= 1.5.0)
  net-http-persistent (= 4.0.1)

BUNDLED WITH
   2.2.15

not_working.rb

#!/usr/bin/env ruby

require "rubygems"
require "bundler/setup"

require "faraday"

connection = Faraday.new("https://google.com") do |f|
  f.adapter :net_http_persistent
end

connection.get("/") do |request|
  request.options.on_data = Proc.new do |chunk, overall_received_bytes|
    puts "Received #{overall_received_bytes} characters"
  end
end

# => (no output)

working.rb

#!/usr/bin/env ruby

require "rubygems"
require "bundler/setup"

require "faraday"

connection = Faraday.new("https://google.com")
connection.get("/") do |request|
  request.options.on_data = Proc.new do |chunk, overall_received_bytes|
    puts "Received #{overall_received_bytes} characters"
  end
end

# => Received 220 characters