Writing TestCase for CSV import rake task - ruby-on-rails

Question

I have a simple rails application where I import data from csv into my rails app which is functioning properly, but I have no idea where to start with testing this rake task, as well as where in a modular rails app. Any help would be appreciated. Thanks!
Hint
My Rails structure is a little different from traditional rails structures, as I have written a Modular Rails App. My structure is in the picture below:
engines/csv_importer/lib/tasks/web_import.rake
The rake task that imports from csv..
require 'open-uri'
require 'csv'
namespace :web_import do
desc 'Import users from csv'
task users: :environment do
url = 'http://blablabla.com/content/people.csv'
# I forced encoding so avoid UndefinedConversionError "\xC3" from ASCII-8BIT to UTF-8
csv_string = open(url).read.force_encoding('UTF-8')
counter = 0
duplicate_counter = 0
user = []
CSV.parse(csv_string, headers: true, header_converters: :symbol) do |row|
next unless row[:name].present? && row[:email_address].present?
user = CsvImporter::User.create row.to_h
if user.persisted?
counter += 1
else
duplicate_counter += 1
end
end
p "Email duplicate record: #{user.email_address} - #{user.errors.full_messages.join(',')}" if user.errors.any?
p "Imported #{counter} users, #{duplicate_counter} duplicate rows ain't added in total"
end
end
Mounted csv_importer in my parent structure
This makes the csv_importer engine available in the root of the application.
Rails.application.routes.draw do
mount CsvImporter::Engine => '/', as: 'csv_importer'
end
To correctly migrate in the root of the application, I added initializer
/engines/csv_importer/lib/csv_importer/engine.rb
module CsvImporter
class Engine < ::Rails::Engine
isolate_namespace CsvImporter
# This enables me to be able to correctly migrate the database from the parent application.
initializer :append_migrations do |app|
unless app.root.to_s.match(root.to_s)
config.paths['db/migrate'].expanded.each do |p|
app.config.paths['db/migrate'] << p
end
end
end
end
end
So with this explanation am able to run rails app like every other rails application. I explained this so anyone who will help will understand what to help me with as regards writing test for the rake task inside the engine.
What I have done as regards writing TEST
task import: [:environment] do
desc 'Import CSV file'
task test: :environment do
# CSV.import 'people.csv'
Rake::Task['app:test:db'].invoke
end
end
How do someone write test for a rake task in a modular app? Thanks!

Answer 1

I haven't worked with engines, but is there a way to just put the CSV importing logic into it's own class?
namespace :web_import do
desc 'Import users from csv'
task users: :environment do
WebImport.new(url: 'http://blablabla.com/content/people.csv').call
end
end
class WebImport # (or whatever name you want)
def initialize(url) ... end
def call
counter, CSV parse, etc...
end
end
That way you can bump into the Rails console to do the WebImport and you can also do a test isolating WebImport. When you do Rake tasks and Jobs (Sidekiq etc), you want to make the Rake task act as as thin a wrapper as possible around the actual meat of the code (which is in this case CSV parsing). Separate the "trigger the csv parse" code from the "actually parse the csv" code into their own classes or files.