diff --git a/Gemfile b/Gemfile
index 36b2b76..44d17b2 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ end
 
 gemspec
 
-gem "rails", "~> 5.1"
+gem "rails", "~> 8.0"
 
 group :development, :test do
   gem 'bootsnap', require: false
@@ -28,6 +28,7 @@ group :development, :test do
   gem 'puma'
   gem 'paperclip', '~> 5.3'
   gem 'dunlop-ember', gitlab: 'benja-2/dunlop-ember', branch: 'master'
+  gem 'record_collection' #, github: 'bterkuile/record_collection', branch: 'master'
 
   #gem 'carrierwave'
   #gem 'fog-aws'
diff --git a/app/services/dunlop/loggable.rb b/app/services/dunlop/loggable.rb
index 934ae5f..a6dbb3c 100644
--- a/app/services/dunlop/loggable.rb
+++ b/app/services/dunlop/loggable.rb
@@ -6,7 +6,7 @@ module Dunlop::Loggable
   end
 
   def with_nested_logger_and_catch_failed(scope=nil, options={})
-    scope ||= caller[0][/`.*'/][1..-2]
+    scope ||= caller[0][/'.*'/][1..-2]
     options[:exception_notifier] = true unless options.has_key?(:exception_notifier)
     backtrace = nil
     ::Dunlop::NestedLogger.scope('empty sandbox', benchmark: false) do
diff --git a/app/services/dunlop/overdue_handling.rb b/app/services/dunlop/overdue_handling.rb
index 618db30..0252223 100644
--- a/app/services/dunlop/overdue_handling.rb
+++ b/app/services/dunlop/overdue_handling.rb
@@ -1,124 +1,126 @@
-module Dunlop::OverdueHandling
-  @registry = {}
-  @final_states = %w[overdue completed rejected]
+module Dunlop
+  module OverdueHandling
+    @registry = {}
+    @final_states = %w[overdue completed rejected]
 
-  def self.registry
-    @registry
-  end
+    def self.registry
+      @registry
+    end
 
-  def self.final_states
-    @final_states
-  end
+    def self.final_states
+      @final_states
+    end
 
-  def self.final_states=(states)
-    @final_states = states
-  end
+    def self.final_states=(states)
+      @final_states = states
+    end
 
-  def self.define(&block)
-    @registry = {} # empty the registry
-    definition_proxy = DefinitionProxy.new
-    definition_proxy.instance_eval(&block)
-  end
+    def self.define(&block)
+      @registry = {} # empty the registry
+      definition_proxy = DefinitionProxy.new
+      definition_proxy.instance_eval(&block)
+    end
 
-  def self.handle_overdue!
-    registry.each do |workflow_step_name, config|
-      base_scope = WorkflowInstance.all #where.not(state: final_states)
-      base_scope = base_scope.where(sti_type: config.scenarios.map{|s| "WorkflowInstance::#{s.to_s.classify}"}) if config.scenarios.any?
-      base_scope = base_scope.joins(workflow_step_name).where.not("#{workflow_step_name.to_s.pluralize}.state" => final_states) #.includes(workflow_step_name)
-      if config.from.is_nested?
-        base_scope = base_scope.joins(config.from.key) if config.from.key != workflow_step_name
-      end
-      base_scope = base_scope.where("#{config.date_target_class.table_name}.#{config.date_target_column} <= ?", Date.current - config.time)
+    def self.handle_overdue!
+      registry.each do |workflow_step_name, config|
+        base_scope = WorkflowInstance.all #where.not(state: final_states)
+        base_scope = base_scope.where(sti_type: config.scenarios.map{|s| "WorkflowInstance::#{s.to_s.classify}"}) if config.scenarios.any?
+        base_scope = base_scope.joins(workflow_step_name).where.not("#{workflow_step_name.to_s.pluralize}.state" => final_states) #.includes(workflow_step_name)
+        if config.from.is_nested?
+          base_scope = base_scope.joins(config.from.key) if config.from.key != workflow_step_name
+        end
+        base_scope = base_scope.where("#{config.date_target_class.table_name}.#{config.date_target_column} <= ?", Date.current - config.time)
 
-      base_scope.find_each do |workflow_instance|
-        next unless workflow_step = workflow_instance.public_send(workflow_step_name)
-        workflow_step.is_overdue!
+        base_scope.find_each do |workflow_instance|
+          next unless workflow_step = workflow_instance.public_send(workflow_step_name)
+          workflow_step.is_overdue!
+        end
       end
     end
-  end
 
-  class DefinitionProxy
-    def when_workflow_step(workflow_step, options = {}, &block)
-      raise "Workflow step #{workflow_step} does not exist" unless WorkflowInstance.possible_workflow_step_names.include?(workflow_step)
-      workflow_step_proxy = WorkflowStepProxy.new(workflow_step, options)
-      workflow_step_proxy.instance_eval(&block) if block
-      workflow_step_proxy.register_callbacks!
-      ::Dunlop::OverdueHandling.registry[workflow_step] = workflow_step_proxy
+    class DefinitionProxy
+      def when_workflow_step(workflow_step, options = {}, &block)
+        raise "Workflow step #{workflow_step} does not exist" unless WorkflowInstance.possible_workflow_step_names.include?(workflow_step)
+        workflow_step_proxy = WorkflowStepProxy.new(workflow_step, options)
+        workflow_step_proxy.instance_eval(&block) if block
+        workflow_step_proxy.register_callbacks!
+        ::Dunlop::OverdueHandling.registry[workflow_step] = workflow_step_proxy
+      end
+
+      def the_final_states_are(states)
+        ::Dunlop::OverdueHandling.final_states = states
+      end
     end
 
-    def the_final_states_are(states)
-      ::Dunlop::OverdueHandling.final_states = states
-    end
-  end
+    class WorkflowStepProxy
+      attr_reader :workflow_step, :options, :overdue_target_class
+      def initialize(workflow_step, options)
+        @workflow_step, @options = workflow_step, options
+        @overdue_target_class = workflow_step.to_s.classify.constantize
+      end
 
-  class WorkflowStepProxy
-    attr_reader :workflow_step, :options, :overdue_target_class
-    def initialize(workflow_step, options)
-      @workflow_step, @options = workflow_step, options
-      @overdue_target_class = workflow_step.to_s.classify.constantize
-    end
+      def date_target_class
+        @date_target_class ||= from.is_nested? ? from.key.to_s.classify.constantize : WorkflowInstance
+      end
 
-    def date_target_class
-      @date_target_class ||= from.is_nested? ? from.key.to_s.classify.constantize : WorkflowInstance
-    end
+      def date_target_column
+        @date_target_column ||= from.field
+      end
 
-    def date_target_column
-      @date_target_column ||= from.field
-    end
+      def scenarios
+        options[:scenarios] || []
+      end
 
-    def scenarios
-      options[:scenarios] || []
-    end
+      def from
+        WorkflowStepBaseDate.new(workflow_step, options[:from])
+      end
 
-    def from
-      WorkflowStepBaseDate.new(workflow_step, options[:from])
-    end
+      def time
+        options[:is]
+      end
 
-    def time
-      options[:is]
-    end
-
-    #TODO: find a simple way to do this!!!
-    def register_callbacks!
-      date_target_classes = [date_target_class] #TODO: only implement on specific scenarios if given as argument
-      date_column = date_target_column
-      workflow_step_name = workflow_step # make local scope for after_save definition
-      overdue_time = time
-      date_target_classes.each do |target_class|
-        target_class.after_save do |record|
-          if saved_changes[date_column]
-            target_record = record.workflow_instance.public_send(workflow_step_name)
-            if date = record.public_send(date_column)
-              if date <= Date.current - overdue_time
-                target_record.is_overdue! if target_record.pending? or target_record.processing?
+      #TODO: find a simple way to do this!!!
+      def register_callbacks!
+        date_target_classes = [date_target_class] #TODO: only implement on specific scenarios if given as argument
+        date_column = date_target_column
+        workflow_step_name = workflow_step # make local scope for after_save definition
+        overdue_time = time
+        date_target_classes.each do |target_class|
+          target_class.after_save do |record|
+            if saved_changes[date_column]
+              target_record = record.workflow_instance.public_send(workflow_step_name)
+              if date = record.public_send(date_column)
+                if date <= Date.current - overdue_time
+                  target_record.is_overdue! if target_record.pending? or target_record.processing?
+                else
+                  target_record.process! if target_record.overdue?
+                end
               else
                 target_record.process! if target_record.overdue?
               end
-            else
-              target_record.process! if target_record.overdue?
             end
           end
         end
       end
     end
-  end
 
-  class WorkflowStepBaseDate
-    attr_reader :workflow_step, :config
-    def initialize(workflow_step, config)
-      @workflow_step, @config = workflow_step, config
-    end
+    class WorkflowStepBaseDate
+      attr_reader :workflow_step, :config
+      def initialize(workflow_step, config)
+        @workflow_step, @config = workflow_step, config
+      end
 
-    def is_nested?
-      config.is_a?(Hash)
-    end
+      def is_nested?
+        config.is_a?(Hash)
+      end
 
-    def key
-      is_nested? ? config.keys.first : config
-    end
+      def key
+        is_nested? ? config.keys.first : config
+      end
 
-    def field
-      is_nested? ? config.values.first : config
+      def field
+        is_nested? ? config.values.first : config
+      end
     end
   end
 end
diff --git a/bin/rails b/bin/rails
index e22bfcc..a97d4f2 100755
--- a/bin/rails
+++ b/bin/rails
@@ -3,6 +3,7 @@
 
 ENGINE_ROOT = File.expand_path('../..', __FILE__)
 ENGINE_PATH = File.expand_path('../../lib/dunlop/engine', __FILE__)
+APP_PATH    = File.expand_path("../spec/dummy/config/application", __dir__)
 
 # Set up gems listed in the Gemfile.
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
diff --git a/dunlop-core.gemspec b/dunlop-core.gemspec
index 0d59659..413d41a 100644
--- a/dunlop-core.gemspec
+++ b/dunlop-core.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency "rails", ">= 4.2.6"
   s.add_dependency 'slim-rails'
-  #s.add_dependency 'record_collection', '>= 0.10.4'
+  #s.add_dependency 'record_collection', '>= 0.10.4' # Only in Gemfile to make not requried
   s.add_dependency 'request_store'
   s.add_dependency 'ransack'
   s.add_dependency 'responders'
@@ -31,6 +31,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'facets'
   s.add_dependency 'memoist'
   s.add_dependency 'cancancan'
+  s.add_dependency 'csv'
 
   # assets
   #s.add_dependency 'momentjs-rails'
diff --git a/lib/generators/dunlop/install/base/base_generator.rb b/lib/generators/dunlop/install/base/base_generator.rb
index c164d85..3d41ba5 100644
--- a/lib/generators/dunlop/install/base/base_generator.rb
+++ b/lib/generators/dunlop/install/base/base_generator.rb
@@ -36,8 +36,8 @@ class Dunlop::Install::BaseGenerator < Rails::Generators::Base
     config.application_name = "#{Rails.application.class.name.deconstantize}"
 
     config.git_version = Rails.env
-    config.git_version = File.read('REVISION').strip if File.exists?('REVISION')
-    config.git_version = File.read('OFFLINE_REVISION').strip if File.exists?('OFFLINE_REVISION')
+    config.git_version = File.read('REVISION').strip if File.exist?('REVISION')
+    config.git_version = File.read('OFFLINE_REVISION').strip if File.exist?('OFFLINE_REVISION')
 
     RUBY
     end
diff --git a/spec/dummy/app/assets/config/manifest.js b/spec/dummy/app/assets/config/manifest.js
new file mode 100644
index 0000000..89c89e7
--- /dev/null
+++ b/spec/dummy/app/assets/config/manifest.js
@@ -0,0 +1,3 @@
+  //= link_tree ../images
+  //= link_directory ../javascripts .js
+  //= link_directory ../stylesheets .css
diff --git a/spec/dummy/app/models/owner_initialization.rb b/spec/dummy/app/models/owner_initialization.rb
index 0ede1be..3d0297f 100644
--- a/spec/dummy/app/models/owner_initialization.rb
+++ b/spec/dummy/app/models/owner_initialization.rb
@@ -1,8 +1,8 @@
 class OwnerInitialization < ApplicationRecord
   include WorkflowStepModel
 
-  serialize :window_from, DayTimeMinutes
-  serialize :window_to,   DayTimeMinutes
+  serialize :window_from, coder: DayTimeMinutes
+  serialize :window_to,   coder: DayTimeMinutes
 
   activate_dunlop!
 end
diff --git a/spec/dummy/config/application.rb b/spec/dummy/config/application.rb
index 44c25a6..1c29cb1 100644
--- a/spec/dummy/config/application.rb
+++ b/spec/dummy/config/application.rb
@@ -22,8 +22,8 @@ module Dummy
     config.application_name = 'Dunlop'
 
     config.git_version = nil
-    config.git_version = File.read('REVISION').strip if File.exists?('REVISION')
-    config.git_version = File.read('OFFLINE_REVISION').strip if File.exists?('OFFLINE_REVISION')
+    config.git_version = File.read('REVISION').strip if File.exist?('REVISION')
+    config.git_version = File.read('OFFLINE_REVISION').strip if File.exist?('OFFLINE_REVISION')
 
     config.file_storage_path = Rails.root.join('files') # source file storage
     config.working_path = '/tmp' # source file processing directory
diff --git a/spec/dummy/config/initializers/dunlop_overdue_config.rb b/spec/dummy/config/initializers/dunlop_overdue_config.rb
index b6e4d49..60426d1 100644
--- a/spec/dummy/config/initializers/dunlop_overdue_config.rb
+++ b/spec/dummy/config/initializers/dunlop_overdue_config.rb
@@ -1,3 +1,5 @@
-Dunlop::OverdueHandling.define do
-  when_workflow_step :contractor_initialization, is: 2.days, from: {owner_initialization: :plan_date}
+Rails.application.config.after_initialize do
+  Dunlop::OverdueHandling.define do
+    when_workflow_step :contractor_initialization, is: 2.days, from: {owner_initialization: :plan_date}
+  end
 end
diff --git a/spec/dummy/config/initializers/dunlop_workflow_config.rb b/spec/dummy/config/initializers/dunlop_workflow_config.rb
index 9e24c2a..09e403c 100644
--- a/spec/dummy/config/initializers/dunlop_workflow_config.rb
+++ b/spec/dummy/config/initializers/dunlop_workflow_config.rb
@@ -1,3 +1,5 @@
-Dunlop::Workflow.configure do |config|
-  config.max_number_of_records_in_display_badge = 72
+Rails.application.config.after_initialize do
+  Dunlop::Workflow.configure do |config|
+    config.max_number_of_records_in_display_badge = 72
+  end
 end
diff --git a/spec/dummy/config/initializers/dunlop_workflow_steps_in_batch_finished_config.rb b/spec/dummy/config/initializers/dunlop_workflow_steps_in_batch_finished_config.rb
index 273a0d0..b1ad5ca 100644
--- a/spec/dummy/config/initializers/dunlop_workflow_steps_in_batch_finished_config.rb
+++ b/spec/dummy/config/initializers/dunlop_workflow_steps_in_batch_finished_config.rb
@@ -1,28 +1,30 @@
-Dunlop::WorkflowStepsInBatchFinished.define do
-  the_final_states_are %w[rejected completed]
+Rails.application.config.after_initialize do
+  Dunlop::WorkflowStepsInBatchFinished.define do
+    the_final_states_are %w[rejected completed]
 
-  on_finishing_of :owner_initialization do
-    description "Send notification mail to Owner" do |workflow_instance_batch|
-      OwnerMailer.owner_initialization_finished(workflow_instance_batch, self).deliver_later
+    on_finishing_of :owner_initialization do
+      description "Send notification mail to Owner" do |workflow_instance_batch|
+        OwnerMailer.owner_initialization_finished(workflow_instance_batch, self).deliver_later
+      end
     end
+
+    #on_finishing_of :contractor_service_window1_execution do
+    #  description <<-DESCRIPTION
+    #    Check ${attributes.owner_service_window2_preparation.migration_file_for_bvt_ready}
+    #    for ${models.owner_service_window2_preparation} workflow steps in the batch
+    #  DESCRIPTION
+    #  action do |workflow_instance_batch|
+    #    workflow_steps_in_batch_scope(:owner_service_window2_preparation).update_all migration_file_for_bvt_ready: true
+    #  end
+
+    #  description "Send an email to Core Delivery informing them of batch completion" do |workflow_instance_batch|
+    #    KpnCoreDeliveryMailer.contractor_service_window1_handled_for_batch(workflow_instance_batch.id).deliver_later
+    #  end
+
+    #  description "Send an email to Schuuring informing them of batch completion" do |workflow_instance_batch|
+    #    SchuuringMailer.workflow_instance_batch_workflow_step_finished(self.class.name, workflow_instance_batch.id).deliver_later
+    #  end
+    #end
+
   end
-
-  #on_finishing_of :contractor_service_window1_execution do
-  #  description <<-DESCRIPTION
-  #    Check ${attributes.owner_service_window2_preparation.migration_file_for_bvt_ready}
-  #    for ${models.owner_service_window2_preparation} workflow steps in the batch
-  #  DESCRIPTION
-  #  action do |workflow_instance_batch|
-  #    workflow_steps_in_batch_scope(:owner_service_window2_preparation).update_all migration_file_for_bvt_ready: true
-  #  end
-
-  #  description "Send an email to Core Delivery informing them of batch completion" do |workflow_instance_batch|
-  #    KpnCoreDeliveryMailer.contractor_service_window1_handled_for_batch(workflow_instance_batch.id).deliver_later
-  #  end
-
-  #  description "Send an email to Schuuring informing them of batch completion" do |workflow_instance_batch|
-  #    SchuuringMailer.workflow_instance_batch_workflow_step_finished(self.class.name, workflow_instance_batch.id).deliver_later
-  #  end
-  #end
-
 end
diff --git a/spec/factories/target_files.rb b/spec/factories/target_files.rb
index 365535c..6eb871f 100644
--- a/spec/factories/target_files.rb
+++ b/spec/factories/target_files.rb
@@ -3,7 +3,7 @@ FactoryBot.define do
     original_file { Tempfile.new("target_file_factory") }
     trait :failed do
       after(:build) { |record| record.log_entries.build(body: 'ERROR - some reason to fail') }
-      state 'failed'
+      state { 'failed' }
     end
   end
 
diff --git a/spec/factories/users.rb b/spec/factories/users.rb
index 71114d9..ea56e9a 100644
--- a/spec/factories/users.rb
+++ b/spec/factories/users.rb
@@ -6,14 +6,14 @@ FactoryBot.define do
 
   factory :user do
     email
-    password 'password'
-    role_names %w[read-class-WorkflowInstance]
+    password   { 'password' }
+    role_names { %w[read-class-WorkflowInstance] }
   end
 
   factory :admin, class: User do
-    email 'admin@example.com'
-    password 'password'
-    admin true
+    email    { 'admin@example.com' }
+    password { 'password' }
+    admin    { true }
   end
 end
 
diff --git a/spec/factories/workflow_instance.rb b/spec/factories/workflow_instance.rb
index b31aa67..28f89b0 100644
--- a/spec/factories/workflow_instance.rb
+++ b/spec/factories/workflow_instance.rb
@@ -1,29 +1,29 @@
 FactoryBot.define do
   factory :workflow_instance do
     after(:build){|instance| instance.setup_workflow_steps }
-    state "unplanned" # default for Vula
+    state  { "unplanned" } # default for Vula
 
     trait :uncategorized do
-        state 'uncategorized'
+        state { 'uncategorized' }
     end
 
     trait :unplanned do
-      state 'unplanned'
+      state { 'unplanned' }
     end
 
     trait :planned do
-      state 'planned'
+      state { 'planned' }
     end
 
     trait :active do
-      state 'active'
+      state { 'active' }
       after :build do |instance|
         instance.workflow_steps.first.state = 'processing'
       end
     end
 
     trait :overdue do
-      state 'overdue'
+      state { 'overdue' }
       after :build do |instance|
         instance.owner_initialization.plan_date = 1.year.ago
         instance.contractor_initialization.state = 'overdue'
@@ -31,14 +31,14 @@ FactoryBot.define do
     end
 
     trait :all_completed do
-      state 'all_completed'
+      state { 'all_completed' }
       after :build do |instance|
         instance.workflow_steps.each{|workflow_step| workflow_step.state = 'completed' }
       end
     end
 
     trait :any_rejected do
-      state 'any_rejected'
+      state { 'any_rejected' }
       after :build do |instance|
         instance.workflow_steps.first.state = 'rejected'
       end
diff --git a/spec/models/dunlop/execution_batch_spec.rb b/spec/models/execution_batch_spec.rb
similarity index 98%
rename from spec/models/dunlop/execution_batch_spec.rb
rename to spec/models/execution_batch_spec.rb
index d27be63..44441e1 100644
--- a/spec/models/dunlop/execution_batch_spec.rb
+++ b/spec/models/execution_batch_spec.rb
@@ -1,6 +1,6 @@
 require 'rails_helper'
 
-describe Dunlop::ExecutionBatch do
+describe ::ExecutionBatch do
   let(:time) { '1981-03-09T13:33:04Z'.to_time }
   let(:model) { ExecutionBatch::MyBatch }
   before { Timecop.freeze time }
diff --git a/spec/rails_helper.rb b/spec/rails_helper.rb
index d1df211..9bd90ac 100644
--- a/spec/rails_helper.rb
+++ b/spec/rails_helper.rb
@@ -43,7 +43,7 @@ RSpec::Support::ObjectFormatter.default_instance.max_formatted_output_length = 1
 
 RSpec.configure do |config|
   # Remove this line if you're not using ActiveRecord or ActiveRecord fixtures
-  config.fixture_path = Dunlop::Engine.root.join("spec/fixtures")
+  config.fixture_paths = [Dunlop::Engine.root.join("spec/fixtures")]
   config.expect_with(:rspec) { |c| c.syntax = [:should, :expect] }
 
 
diff --git a/spec/services/dunlop/file_zip_spec.rb b/spec/services/dunlop/file_zip_spec.rb
index eee1a13..e84d6fc 100644
--- a/spec/services/dunlop/file_zip_spec.rb
+++ b/spec/services/dunlop/file_zip_spec.rb
@@ -20,10 +20,10 @@ RSpec.describe Dunlop::FileZip do
     context "mime-type: application/zip" do
 
       it "unzips the file to the provided filename" do
-        expect(File.exists?(destination_filename)).to be_falsey
+        expect(File.exist?(destination_filename)).to be_falsey
         subject.unzip(zipped_filename, destination_filename)
-        expect(File.exists?(destination_filename)).to be_truthy
-        expect(File.exists?(zipped_filename)).to be_truthy
+        expect(File.exist?(destination_filename)).to be_truthy
+        expect(File.exist?(zipped_filename)).to be_truthy
         expect(File.read(destination_filename)).to eq File.read(unzipped_filename)
       end
 
@@ -34,10 +34,10 @@ RSpec.describe Dunlop::FileZip do
     context "mime-type: application/x-gzip" do
 
       it "unzips the file to the provided filename" do
-        expect(File.exists?(destination_filename)).to be_falsey
+        expect(File.exist?(destination_filename)).to be_falsey
         subject.unzip(gzipped_filename, destination_filename)
-        expect(File.exists?(destination_filename)).to be_truthy
-        expect(File.exists?(gzipped_filename)).to be_truthy
+        expect(File.exist?(destination_filename)).to be_truthy
+        expect(File.exist?(gzipped_filename)).to be_truthy
         expect(File.read(destination_filename)).to eq File.read(unzipped_filename)
       end
 
@@ -46,10 +46,10 @@ RSpec.describe Dunlop::FileZip do
     context "mime-type: text/plain" do
 
       it "copies the file to the provided filename" do
-        expect(File.exists?(destination_filename)).to be_falsey
+        expect(File.exist?(destination_filename)).to be_falsey
         subject.unzip(unzipped_filename, destination_filename)
-        expect(File.exists?(destination_filename)).to be_truthy
-        expect(File.exists?(unzipped_filename)).to be_truthy
+        expect(File.exist?(destination_filename)).to be_truthy
+        expect(File.exist?(unzipped_filename)).to be_truthy
         expect(File.read(destination_filename)).to eq File.read(unzipped_filename)
       end
 
@@ -69,10 +69,10 @@ RSpec.describe Dunlop::FileZip do
     end
 
     it "gzips the file to the provided filename" do
-      expect(File.exists?(gzipped_filename)).to be_falsey
+      expect(File.exist?(gzipped_filename)).to be_falsey
       subject.gzip(unzipped_filename, gzipped_filename)
-      expect(File.exists?(gzipped_filename)).to be_truthy
-      expect(File.exists?(unzipped_filename)).to be_truthy
+      expect(File.exist?(gzipped_filename)).to be_truthy
+      expect(File.exist?(unzipped_filename)).to be_truthy
 
       expect(File.size(unzipped_filename)).to eq 305
       expect(File.size(gzipped_filename)).to eq 153