Write rspec for rake task

i have task /lib/crawler.rake like that:

namespace :crawler do
  area_names = Dir[Rails.root.join("lib", "crawler", "*.rb")].map do |file_name|
    File.basename(file_name, ".rb")
  end

  area_names.each do |area_name|
    task area_name.to_sym => :environment do
      logger = Logger.new("log/crawl_#{area_name}.log")

      # do something

      parallel_results = crawler.crawl
      mutex = Mutex.new

      Parallel.each(parallel_results, in_threads: [parallel_results.count, CRAWL_CONFIG["building_thread_max"]].min) do |pages|
        begin
          # do something
        rescue => e
          # do something
          raise e
        end
      end

      Availability.update_by_grounds_and_time
    end
  end
end

Logic here, if everything's ok after parallel, we'll call update_by_grounds_and_time method to update Availability; if get error, we'll stop action and raise error.

So i want to write rspec to test for these cases, i want to mock/stub output of task here (pass or raise error) and check did we call update_by_grounds_and_time method? Can we don't need invoke really task? can we use Rspec Mock?

Can you help me! Thank

If it is defined in Rakefile, try this:

require 'rake'

RSpec.describe "Rake Tasks" do
  before do
    file, path = Rake.application.find_rakefile_location
    Rake.load_rakefile("#{path}/#{file}")
  end

  it "should invoke some tasks" do
    expect(Availability).to receive(:update_by_grounds_and_time)
    Rake.application["crawler:#{area_name}"].invoke
  end
end

If it is defined in foo.rake, then try this one:

require 'rake'

RSpec.describe "Rake Tasks" do
  before do
    Rake.application.rake_require('/path/to/lib/tasks/foo')
  end

  it "should invoke some tasks" do
    expect(Availability).to receive(:update_by_grounds_and_time)
    Rake.application["crawler:#{area_name}"].invoke
  end
end

UPDATE (error case)

For example

# foo.rake
Parallel.each(parallel_results, in_threads: [parallel_results.count, CRAWL_CONFIG["building_thread_max"]].min) do |pages|
  begin
    foo = Foo.new
    foo.bar
    # do something else
  rescue => e
    # do something
    raise e
  end
end

# foo_spec.rb
require 'rake'

RSpec.describe "Rake Tasks" do
  before do
    Rake.application.rake_require('/path/to/lib/tasks/foo')
  end

  it "should not call Availability#update_by_grounds_and_time if error raised" do
    allow_any_instance_of(Foo).to receive(:bar).and_raise(StandardError)
    expect(Availability).to_not receive(:update_by_grounds_and_time)
    expect { Rake.application["crawler:#{area_name}"].invoke }.to raise_error(StandardError)
  end
end