diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index e25cb2ae..9c389afd 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -7,7 +7,7 @@ class ApplicationController < ActionController::Base
   MEMBER_ACTIONS = %i[destroy edit show update].freeze
   RENDER_HOST = CodeOcean::Config.new(:code_ocean).read[:render_host]
   LEGAL_SETTINGS = CodeOcean::Config.new(:code_ocean).read[:legal] || {}
-  MONITORING_USER_AGENT = Regexp.compile(/updown\.io/).freeze
+  MONITORING_USER_AGENT = /updown\.io/
 
   before_action :deny_access_from_render_host
   after_action :verify_authorized, except: %i[welcome]
diff --git a/app/services/proforma_service/import.rb b/app/services/proforma_service/import.rb
index c58eccab..b9598e26 100644
--- a/app/services/proforma_service/import.rb
+++ b/app/services/proforma_service/import.rb
@@ -67,7 +67,7 @@ module ProformaService
         zip_file.map(&:name)
       end
 
-      filenames.select {|f| f[/\.xml$/] }.any?
+      filenames.any? {|f| f[/\.xml$/] }
     rescue Zip::Error
       raise Proforma::InvalidZip
     end
diff --git a/db/migrate/20220415215112_migrate_testruns.rb b/db/migrate/20220415215112_migrate_testruns.rb
index fae26575..fa3435c7 100644
--- a/db/migrate/20220415215112_migrate_testruns.rb
+++ b/db/migrate/20220415215112_migrate_testruns.rb
@@ -4,17 +4,17 @@ class MigrateTestruns < ActiveRecord::Migration[6.1]
   # We are not changing any tables but only backfilling data.
   disable_ddl_transaction!
 
-  SPLIT_OUTPUT = Regexp.compile(/(?<meta>message: (?<message>.*)\n|status: (?<status>.*)\n)? stdout: (?<stdout>.*)\n stderr: ?(?<stderr>.*)/m)
-  PYTHON_BYTE_OUTPUT = Regexp.compile(/^b'(?<raw_output>.*)'$/)
-  PYTHON_JSON_OUTPUT = Regexp.compile(/{"cmd":"write","stream":"(?<stream>.*)","data":"(?<data_output>.*)"}/)
-  RUN_OUTPUT = Regexp.compile(%r{(?<prefix>timeout:)? ?(?>make run\r\n)?(?>python3 /usr/lib/[^\r\n]*\r\n|/usr/bin/python3[^\r\n]*\r\n|ruby [^\r\n]*\r\n)?(?<cleaned_output>[^ "\e][^\e]*?[^#\e])?(?<shell>\r\e.*?)?#?(?<suffix>exit|timeout)?\r?\Z}m)
-  REAL_EXIT = Regexp.compile(/\A(?>(?<json>(?<json_output>{".*?)?(?>{"cmd":(?> |"write","stream":"stdout","data":)?"#?exit(?>\\[nr])?"})+(?<more_shell_output_after_json>.*))|(?<program_output>.*?)(?>#?exit\s*)+(?<more_shell_output_after_program>.*))\z/m)
-  STDERR_WRITTEN = Regexp.compile(/^(?:(?<rb_error>\r*[^\n\r]*\.rb:\d+:.*)|(?<other_error>\r*[^\n\r]*\.java:\d+: error.*|\r*Exception in thread.*|\r*There was .*|\r*[^\n\r]*java\.lang\..*|\r*make: \*\*\* \[.*))\z/m)
-  FIND_JSON = Regexp.compile(/{(?:(?:"(?:\\.|[^\\"])+?"\s*:\s*(?:"(?:\\.|[^\\"])*?"|-?\d++(?:\.\d++)?|\[.*?\]|{.*?}|null))+?\s*,?\s*)+}/)
+  SPLIT_OUTPUT = /(?<meta>message: (?<message>.*)\n|status: (?<status>.*)\n)? stdout: (?<stdout>.*)\n stderr: ?(?<stderr>.*)/m
+  PYTHON_BYTE_OUTPUT = /^b'(?<raw_output>.*)'$/
+  PYTHON_JSON_OUTPUT = /{"cmd":"write","stream":"(?<stream>.*)","data":"(?<data_output>.*)"}/
+  RUN_OUTPUT = %r{(?<prefix>timeout:)? ?(?>make run\r\n)?(?>python3 /usr/lib/[^\r\n]*\r\n|/usr/bin/python3[^\r\n]*\r\n|ruby [^\r\n]*\r\n)?(?<cleaned_output>[^ "\e][^\e]*?[^#\e])?(?<shell>\r\e.*?)?#?(?<suffix>exit|timeout)?\r?\Z}m
+  REAL_EXIT = /\A(?>(?<json>(?<json_output>{".*?)?(?>{"cmd":(?> |"write","stream":"stdout","data":)?"#?exit(?>\\[nr])?"})+(?<more_shell_output_after_json>.*))|(?<program_output>.*?)(?>#?exit\s*)+(?<more_shell_output_after_program>.*))\z/m
+  STDERR_WRITTEN = /^(?:(?<rb_error>\r*[^\n\r]*\.rb:\d+:.*)|(?<other_error>\r*[^\n\r]*\.java:\d+: error.*|\r*Exception in thread.*|\r*There was .*|\r*[^\n\r]*java\.lang\..*|\r*make: \*\*\* \[.*))\z/m
+  FIND_JSON = /{(?:(?:"(?:\\.|[^\\"])+?"\s*:\s*(?:"(?:\\.|[^\\"])*?"|-?\d++(?:\.\d++)?|\[.*?\]|{.*?}|null))+?\s*,?\s*)+}/
   # We identify incomplete Unicode characters. Valid unicode characters are:
   # \uXXXX, \u{XXXXX}, \udYXX\udZXX with X = 0-9a-f, Y = 89ab, Z = cdef
   # Every incomplete prefix of a valid unicode character is identified
-  REPLACE_INCOMPLETE_UNICODE = Regexp.compile(/(?:\\?\\u[\da-f]{0,3}|\\?\\ud[89ab][\da-f]{2}\\?(?:\\(?:u(?:d(?:[cdef][\da-f]?)?)?)?)?|\\?\\u\{[\da-f]{0,4})"}\z/)
+  REPLACE_INCOMPLETE_UNICODE = /(?:\\?\\u[\da-f]{0,3}|\\?\\ud[89ab][\da-f]{2}\\?(?:\\(?:u(?:d(?:[cdef][\da-f]?)?)?)?)?|\\?\\u\{[\da-f]{0,4})"}\z/
 
   # NOTE: `update_columns` won't run validations nor update the `updated_at` timestamp.
   # This is what we want here, thus we disable Rubocop for this migration.
diff --git a/lib/runner/connection/buffer.rb b/lib/runner/connection/buffer.rb
index 2a5dd838..03b358bd 100644
--- a/lib/runner/connection/buffer.rb
+++ b/lib/runner/connection/buffer.rb
@@ -6,7 +6,7 @@ class Runner::Connection::Buffer
   # substring either in single or double quotes (e.g., within a JSON). Originally, each line break consists of `\r\n`.
   # We keep the `\r` at the end of the line (keeping "empty" lines) and replace it after buffering.
   # Inspired by https://stackoverflow.com/questions/13040585/split-string-by-spaces-properly-accounting-for-quotes-and-backslashes-ruby
-  SPLIT_INDIVIDUAL_LINES = Regexp.compile(/(?:"(?:\\"|[^"])*"|'(?:\\'|[^'])*'|[^\n])+/)
+  SPLIT_INDIVIDUAL_LINES = /(?:"(?:\\"|[^"])*"|'(?:\\'|[^'])*'|[^\n])+/
 
   def initialize
     @global_buffer = +''
diff --git a/spec/factories/code_ocean/file.rb b/spec/factories/code_ocean/file.rb
index 6b173268..5d8606fb 100644
--- a/spec/factories/code_ocean/file.rb
+++ b/spec/factories/code_ocean/file.rb
@@ -6,15 +6,15 @@ module CodeOcean
   FactoryBot.define do
     factory :file, class: 'CodeOcean::File' do
       content { '' }
-      association :context, factory: :submission
-      association :file_type, factory: :dot_rb
+      context factory: :submission
+      file_type factory: :dot_rb
       hidden { false }
       name { SecureRandom.hex }
       read_only { false }
       role { 'main_file' }
 
       trait(:image) do
-        association :file_type, factory: :dot_png
+        file_type factory: :dot_png
         name { 'poster' }
         native_file { Rack::Test::UploadedFile.new(Rails.root.join('db/seeds/audio_video/poster.png'), 'image/png') }
       end
@@ -22,8 +22,8 @@ module CodeOcean
 
     factory :test_file, class: 'CodeOcean::File' do
       content { '' }
-      association :context, factory: :dummy
-      association :file_type, factory: :dot_rb
+      context factory: :dummy
+      file_type factory: :dot_rb
       hidden { true }
       name { SecureRandom.hex }
       read_only { true }
diff --git a/spec/factories/codeharbor_link.rb b/spec/factories/codeharbor_link.rb
index 692a2aeb..e2238e0e 100644
--- a/spec/factories/codeharbor_link.rb
+++ b/spec/factories/codeharbor_link.rb
@@ -2,7 +2,7 @@
 
 FactoryBot.define do
   factory :codeharbor_link do
-    user { build(:teacher) }
+    user factory: :teacher
     push_url { 'https://push.url' }
     check_uuid_url { 'https://check-uuid.url' }
     sequence(:api_key) {|n| "api_key#{n}" }
diff --git a/spec/factories/error_templates.rb b/spec/factories/error_templates.rb
index a0556912..c0f2ecaa 100644
--- a/spec/factories/error_templates.rb
+++ b/spec/factories/error_templates.rb
@@ -2,7 +2,7 @@
 
 FactoryBot.define do
   factory :error_template do
-    association :execution_environment, factory: :ruby
+    execution_environment factory: :ruby
     name { 'MyString' }
     signature { 'MyString' }
   end
diff --git a/spec/factories/external_user.rb b/spec/factories/external_user.rb
index e6d5f0f2..3d4427f0 100644
--- a/spec/factories/external_user.rb
+++ b/spec/factories/external_user.rb
@@ -2,7 +2,7 @@
 
 FactoryBot.define do
   factory :external_user do
-    association :consumer
+    consumer
     generated_email
     external_id { SecureRandom.uuid }
     generated_user_name
diff --git a/spec/factories/internal_user.rb b/spec/factories/internal_user.rb
index b6166061..c52bf94e 100644
--- a/spec/factories/internal_user.rb
+++ b/spec/factories/internal_user.rb
@@ -3,7 +3,7 @@
 FactoryBot.define do
   factory :admin, class: 'InternalUser' do
     activated_user
-    association :consumer
+    consumer
     email { 'admin@example.org' }
     generated_user_name
     password { 'admin' }
@@ -17,7 +17,7 @@ FactoryBot.define do
 
   factory :teacher, class: 'InternalUser' do
     activated_user
-    association :consumer
+    consumer
     generated_email
     generated_user_name
     password { 'teacher' }
@@ -31,7 +31,7 @@ FactoryBot.define do
 
   factory :learner, class: 'InternalUser' do
     activated_user
-    association :consumer
+    consumer
     generated_email
     generated_user_name
     password { 'learner' }
diff --git a/spec/factories/lti_parameter.rb b/spec/factories/lti_parameter.rb
index df23526c..0eda270f 100644
--- a/spec/factories/lti_parameter.rb
+++ b/spec/factories/lti_parameter.rb
@@ -8,9 +8,9 @@ FactoryBot.define do
   }.freeze
 
   factory :lti_parameter do
-    association :consumer
-    association :exercise, factory: :math
-    association :external_user
+    consumer
+    exercise factory: :math
+    external_user
 
     lti_parameters { lti_params }
 
diff --git a/spec/factories/request_for_comment.rb b/spec/factories/request_for_comment.rb
index e6b15067..b6dc4ed2 100644
--- a/spec/factories/request_for_comment.rb
+++ b/spec/factories/request_for_comment.rb
@@ -2,10 +2,10 @@
 
 FactoryBot.define do
   factory :rfc, class: 'RequestForComment' do
-    association :user, factory: :external_user
-    association :exercise, factory: :math
+    user factory: :external_user
+    exercise factory: :math
     submission { association :submission, exercise:, user: }
-    association :file
+    file
     sequence :question do |n|
       "test question #{n}"
     end
diff --git a/spec/factories/runner.rb b/spec/factories/runner.rb
index 28c6ffd9..3ce0941f 100644
--- a/spec/factories/runner.rb
+++ b/spec/factories/runner.rb
@@ -4,7 +4,7 @@
 FactoryBot.define do
   factory :runner do
     runner_id { SecureRandom.uuid }
-    association :execution_environment, factory: :ruby
-    association :user, factory: :external_user
+    execution_environment factory: :ruby
+    user factory: :external_user
   end
 end
diff --git a/spec/factories/shared_traits.rb b/spec/factories/shared_traits.rb
index 9bf58648..52bcbd5f 100644
--- a/spec/factories/shared_traits.rb
+++ b/spec/factories/shared_traits.rb
@@ -3,7 +3,7 @@
 FactoryBot.define do
   %i[admin external_user teacher].each do |factory_name|
     trait :"created_by_#{factory_name}" do
-      association :user, factory: factory_name
+      user factory: factory_name
     end
   end
 
diff --git a/spec/factories/structured_error_attributes.rb b/spec/factories/structured_error_attributes.rb
index 6349580d..00727896 100644
--- a/spec/factories/structured_error_attributes.rb
+++ b/spec/factories/structured_error_attributes.rb
@@ -2,8 +2,8 @@
 
 FactoryBot.define do
   factory :structured_error_attribute do
-    association :structured_error
-    association :error_template_attribute
+    structured_error
+    error_template_attribute
     value { 'MyString' }
   end
 end
diff --git a/spec/factories/structured_errors.rb b/spec/factories/structured_errors.rb
index 921e8ff6..4d716ec4 100644
--- a/spec/factories/structured_errors.rb
+++ b/spec/factories/structured_errors.rb
@@ -2,7 +2,7 @@
 
 FactoryBot.define do
   factory :structured_error do
-    association :error_template
-    association :submission
+    error_template
+    submission
   end
 end
diff --git a/spec/factories/study_group.rb b/spec/factories/study_group.rb
index be4ad0ae..f933af04 100644
--- a/spec/factories/study_group.rb
+++ b/spec/factories/study_group.rb
@@ -2,7 +2,7 @@
 
 FactoryBot.define do
   factory :study_group, class: 'StudyGroup' do
-    association :consumer
+    consumer
     sequence :name do |n|
       "TestGroup#{n}"
     end
diff --git a/spec/factories/submission.rb b/spec/factories/submission.rb
index 39f9f338..28f841ed 100644
--- a/spec/factories/submission.rb
+++ b/spec/factories/submission.rb
@@ -4,7 +4,7 @@ FactoryBot.define do
   factory :submission do
     cause { 'save' }
     created_by_external_user
-    association :exercise, factory: :math
+    exercise factory: :math
 
     after(:create) do |submission|
       submission.exercise.files.editable.visible.each do |file|
diff --git a/spec/factories/user_exercise_feedback.rb b/spec/factories/user_exercise_feedback.rb
index 9c8de052..ecad57d2 100644
--- a/spec/factories/user_exercise_feedback.rb
+++ b/spec/factories/user_exercise_feedback.rb
@@ -4,6 +4,6 @@ FactoryBot.define do
   factory :user_exercise_feedback, class: 'UserExerciseFeedback' do
     created_by_external_user
     feedback_text { 'Most suitable exercise ever' }
-    association :exercise, factory: :math
+    exercise factory: :math
   end
 end
diff --git a/spec/policies/request_for_comment_policy_spec.rb b/spec/policies/request_for_comment_policy_spec.rb
index 8305a155..184cc4c3 100644
--- a/spec/policies/request_for_comment_policy_spec.rb
+++ b/spec/policies/request_for_comment_policy_spec.rb
@@ -184,7 +184,7 @@ describe RequestForCommentPolicy do
           end
 
           it 'does not grant access to authors of another primary study groups' do
-            rfc_other_study_group.author.update(study_groups: [create(:study_group)])
+            rfc_other_study_group.author.update(study_groups: create_list(:study_group, 1))
             expect(policy).not_to permit(rfc_other_study_group.author, rfc_other_study_group)
           end