Add test for rails g good_job:install

spec/lib/generators/good_job/install_generator_spec.rb

@@ -0,0 +1,14 @@
+require 'rails_helper'
+require 'generators/good_job/install_generator'
+
+describe GoodJob::InstallGenerator, type: :generator do
+  it 'creates a migration for good_jobs table' do
+    create_dummy_app
+
+    install_good_job
+
+    expect(Dir.glob("#{dummy_app_path}/db/migrate/[0-9]*_create_good_jobs.rb")).not_to be_empty
+
+    remove_dummy_app
+  end
+end

spec/support/good_job_test_helper.rb

@@ -0,0 +1,33 @@
+require 'fileutils'
+
+module GoodJobTestHelper
+  def create_dummy_app
+    FileUtils.cd(tmp_path) do
+      `rails new dummy --skip-action-mailer --skip-action-mailbox --skip-action-cable --skip-sprockets --skip-listen --skip-javascript --skip-turbolinks --skip-system-test --skip-test-unit --skip-bootsnap --skip-spring`
+    end
+  end
+
+  def remove_dummy_app
+    FileUtils.rm_rf(dummy_app_path)
+  end
+
+  def install_good_job
+    File.open("#{dummy_app_path}/Gemfile", 'a') do |f|
+      f.puts "gem 'good_job'"
+    end
+
+    FileUtils.cd(dummy_app_path) do
+      `rails g good_job:install`
+    end
+  end
+
+  def dummy_app_path
+    File.join(tmp_path, 'dummy')
+  end
+
+  def tmp_path
+    @_tmp_path ||= File.join(File.dirname(__FILE__), '..')
+  end
+end
+
+RSpec.configure { |c| c.include GoodJobTestHelper, type: :generator }