guard for destructive rake tasks

destructive.rake

#      _           _                   _   _
#   __| | ___  ___| |_ _ __ _   _  ___| |_(_)_   _____
#  / _` |/ _ \/ __| __| '__| | | |/ __| __| \ \ / / _ \
# | (_| |  __/\__ \ |_| |  | |_| | (__| |_| |\ V /  __/
#  \__,_|\___||___/\__|_|   \__,_|\___|\__|_| \_/ \___|

# handy guard for destructive rake tasks
# just include this before any troublesome task
# typical usage:
#   task :riskytask, [:destructive, :environment] do

# found here:
# http://technotes.iangreenleaf.com/posts/confirmation-for-destructive-rake-tasks.html

class Nope < RuntimeError; end

task :destructive do
  puts 'This task is destructive! Are you sure you want to continue? [y/N]'
  input = $stdin.gets.chomp
  raise Nope unless input.casecmp('y').zero?
end

destructive_spec.rb

RSpec.describe 'rake destructive', type: :task do
  around do |example|
    suppress_stdout(&example)
  end

  it 'has no prerequisites' do
    expect(task.prerequisites).to be_empty
  end

  describe 'warning message' do
    around do |example|
      fake_stdin('y', &example)
    end

    it 'should warn that the task is destructive' do
      expect { task.execute }.to output(/destructive/).to_stdout
    end

    it 'should ask if the user wants to continue' do
      expect { task.execute }.to output(/continue\?/).to_stdout
    end
  end

  describe 'response to input' do
    it 'succeeds when user says y' do
      fake_stdin('y') do
        expect { task.execute }.not_to raise_exception
      end
    end

    it 'succeeds when user says Y (upper case)' do
      fake_stdin('Y') do
        expect { task.execute }.not_to raise_exception
      end
    end

    it 'terminates when user says n' do
      fake_stdin('n') do
        expect { task.execute }.to raise_exception Nope
      end
    end

    it 'terminates when user says N (upper case)' do
      fake_stdin('n') do
        expect { task.execute }.to raise_exception Nope
      end
    end

    it 'terminates when user says neither y nor n' do
      fake_stdin('meh') do
        expect { task.execute }.to raise_exception Nope
      end
    end
  end
end

tasks.rb

# https://www.eliotsykes.com/test-rails-rake-tasks-with-rspec
require 'rake'

# Task names should be used in the top-level describe, with an optional
# "rake "-prefix for better documentation. Both of these will work:
#
# 1) describe "foo:bar" do ... end
#
# 2) describe "rake foo:bar" do ... end
#
# Favor including "rake "-prefix as in the 2nd example above as it produces
# doc output that makes it clear a rake task is under test and how it is
# invoked.
module TaskExampleGroup
  extend ActiveSupport::Concern

  included do
    let(:task_name) { self.class.top_level_description.sub(/\Arake /, '') }
    let(:tasks) { Rake::Task }

    # Make the Rake task available as `task` in your examples:
    subject(:task) { tasks[task_name] }
  end
end

RSpec.configure do |config|
  # Tag Rake specs with `:task` metadata or put them in the spec/tasks dir
  config.define_derived_metadata(file_path: %r{/spec/tasks/}) do |metadata|
    metadata[:type] = :task
  end

  config.include TaskExampleGroup, type: :task

  config.before(:suite) do
    Rails.application.load_tasks
  end
end

fake_stdin for tests found here:

https://gist.github.com/stephancom/b28b373036e80a9dfb3612d1528352fa