diff --git a/app/controllers/api/subscriptions_controller.rb b/app/controllers/api/subscriptions_controller.rb
index 837922a55..9414b57a2 100644
--- a/app/controllers/api/subscriptions_controller.rb
+++ b/app/controllers/api/subscriptions_controller.rb
@@ -15,7 +15,7 @@ class API::SubscriptionsController < API::ApiController
 
   def cancel
     authorize @subscription
-    if @subscription.expire(DateTime.current)
+    if @subscription.expire(Time.current)
       render :show, status: :ok, location: @subscription
     else
       render json: { error: 'already expired' }, status: :unprocessable_entity
diff --git a/app/controllers/open_api/v1/accounting_controller.rb b/app/controllers/open_api/v1/accounting_controller.rb
index b1dfdf02e..8e1942a3f 100644
--- a/app/controllers/open_api/v1/accounting_controller.rb
+++ b/app/controllers/open_api/v1/accounting_controller.rb
@@ -16,8 +16,8 @@ class OpenAPI::V1::AccountingController < OpenAPI::V1::BaseController
     @lines = AccountingLine.order(date: :desc)
                            .includes(:invoicing_profile, invoice: :payment_gateway_object)
 
-    @lines = @lines.where('date >= ?', DateTime.parse(params[:after])) if params[:after].present?
-    @lines = @lines.where('date <= ?', DateTime.parse(params[:before])) if params[:before].present?
+    @lines = @lines.where('date >= ?', Time.zone.parse(params[:after])) if params[:after].present?
+    @lines = @lines.where('date <= ?', Time.zone.parse(params[:before])) if params[:before].present?
     @lines = @lines.where(invoice_id: may_array(params[:invoice_id])) if params[:invoice_id].present?
     @lines = @lines.where(line_type: may_array(params[:type])) if params[:type].present?
 
diff --git a/app/controllers/open_api/v1/subscriptions_controller.rb b/app/controllers/open_api/v1/subscriptions_controller.rb
index 8eb9fd9dd..d6feceb8d 100644
--- a/app/controllers/open_api/v1/subscriptions_controller.rb
+++ b/app/controllers/open_api/v1/subscriptions_controller.rb
@@ -11,8 +11,8 @@ class OpenAPI::V1::SubscriptionsController < OpenAPI::V1::BaseController
                                  .includes(:plan, statistic_profile: :user)
                                  .references(:statistic_profile, :plan)
 
-    @subscriptions = @subscriptions.where('created_at >= ?', DateTime.parse(params[:after])) if params[:after].present?
-    @subscriptions = @subscriptions.where('created_at <= ?', DateTime.parse(params[:before])) if params[:before].present?
+    @subscriptions = @subscriptions.where('created_at >= ?', Time.zone.parse(params[:after])) if params[:after].present?
+    @subscriptions = @subscriptions.where('created_at <= ?', Time.zone.parse(params[:before])) if params[:before].present?
     @subscriptions = @subscriptions.where(plan_id: may_array(params[:plan_id])) if params[:plan_id].present?
     @subscriptions = @subscriptions.where(statistic_profiles: { user_id: may_array(params[:user_id]) }) if params[:user_id].present?
 
diff --git a/app/controllers/open_api/v1/users_controller.rb b/app/controllers/open_api/v1/users_controller.rb
index 0b3f491b8..0d7b32811 100644
--- a/app/controllers/open_api/v1/users_controller.rb
+++ b/app/controllers/open_api/v1/users_controller.rb
@@ -14,7 +14,7 @@ class OpenAPI::V1::UsersController < OpenAPI::V1::BaseController
       @users = @users.where(email: email_param)
     end
     @users = @users.where(id: may_array(params[:user_id])) if params[:user_id].present?
-    @users = @users.where('created_at >= ?', DateTime.parse(params[:created_after])) if params[:created_after].present?
+    @users = @users.where('created_at >= ?', Time.zone.parse(params[:created_after])) if params[:created_after].present?
 
     return if params[:page].blank?
 
diff --git a/app/models/avoir.rb b/app/models/avoir.rb
index 4a656c7b1..09e718e3b 100644
--- a/app/models/avoir.rb
+++ b/app/models/avoir.rb
@@ -17,7 +17,7 @@ class Avoir < Invoice
   end
 
   def expire_subscription
-    user.subscription.expire(DateTime.current)
+    user.subscription.expire(Time.current)
   end
 
   private
diff --git a/app/services/accounting/vat_export_service.rb b/app/services/accounting/vat_export_service.rb
index ee8054d36..932f99733 100644
--- a/app/services/accounting/vat_export_service.rb
+++ b/app/services/accounting/vat_export_service.rb
@@ -82,9 +82,9 @@ class Accounting::VatExportService
     columns.each do |column|
       case column
       when 'start_date'
-        row << DateTime.parse(start_date).strftime(date_format)
+        row << Time.zone.parse(start_date).strftime(date_format)
       when 'end_date'
-        row << DateTime.parse(end_date).strftime(date_format)
+        row << Time.zone.parse(end_date).strftime(date_format)
       when 'vat_rate'
         row << vat_rate.to_s
       when 'amount'
diff --git a/app/services/cart/create_cart_item_service.rb b/app/services/cart/create_cart_item_service.rb
index a4654b29c..3e83da9ee 100644
--- a/app/services/cart/create_cart_item_service.rb
+++ b/app/services/cart/create_cart_item_service.rb
@@ -104,7 +104,7 @@ class Cart::CreateCartItemService
     if cart_subscription
       { subscription: cart_subscription, new_subscription: true }
     elsif @customer.subscribed_plan
-      { subscription: @customer.subscription, new_subscription: false } unless @customer.subscription.expired_at < DateTime.current
+      { subscription: @customer.subscription, new_subscription: false } unless @customer.subscription.expired_at < Time.current
     else
       { subscription: nil, new_subscription: false }
     end
diff --git a/app/services/invoices_service.rb b/app/services/invoices_service.rb
index 97c23eae2..47b96900b 100644
--- a/app/services/invoices_service.rb
+++ b/app/services/invoices_service.rb
@@ -31,7 +31,7 @@ class InvoicesService
     unless filters[:date].nil?
       invoices = invoices.where(
         "date_trunc('day', invoices.created_at) = :search",
-        search: "%#{DateTime.iso8601(filters[:date]).to_time.to_date}%"
+        search: "%#{Time.iso8601(filters[:date]).in_time_zone.to_date}%"
       )
     end
 
diff --git a/app/services/orders/order_service.rb b/app/services/orders/order_service.rb
index 693cbca6f..24d6a4338 100644
--- a/app/services/orders/order_service.rb
+++ b/app/services/orders/order_service.rb
@@ -121,7 +121,7 @@ class Orders::OrderService
     def filter_by_period(orders, filters)
       return orders unless filters[:period_from].present? && filters[:period_to].present?
 
-      orders.where(created_at: DateTime.parse(filters[:period_from])..DateTime.parse(filters[:period_to]).end_of_day)
+      orders.where(created_at: Time.zone.parse(filters[:period_from])..Time.zone.parse(filters[:period_to]).end_of_day)
     end
 
     def orders_ordering(orders, filters)
diff --git a/app/services/payment_document_service.rb b/app/services/payment_document_service.rb
index 0816f5fe8..c4ac219af 100644
--- a/app/services/payment_document_service.rb
+++ b/app/services/payment_document_service.rb
@@ -58,23 +58,19 @@ class PaymentDocumentService
 
     private
 
-    ##
     # Output the given integer with leading zeros. If the given value is longer than the given
     # length, it will be truncated.
-    # @param value {Integer} the integer to pad
-    # @param length {Integer} the length of the resulting string.
-    ##
+    # @param value [Integer] the integer to pad
+    # @param length [Integer] the length of the resulting string.
     def pad_and_truncate(value, length)
       value.to_s.rjust(length, '0').gsub(/^.*(.{#{length},}?)$/m, '\1')
     end
 
-    ##
     # Returns the number of current invoices in the given range around the current date.
     # If range is invalid or not specified, the total number of invoices is returned.
-    # @param range {String} 'day', 'month', 'year'
-    # @param date {Date} the ending date
-    # @return {Integer}
-    ##
+    # @param range [String] 'day', 'month', 'year'
+    # @param date [Date] the ending date
+    # @return [Integer]
     def number_of_invoices(range, date = Time.current)
       case range.to_s
       when 'day'
@@ -94,11 +90,9 @@ class PaymentDocumentService
         Order.where('created_at >= :start_date AND created_at <= :end_date', start_date: start, end_date: ending).length
     end
 
-    ##
     # Replace the date elements in the provided pattern with the date values, from the provided date
-    # @param reference {string}
-    # @param date {DateTime}
-    ##
+    # @param reference [String]
+    # @param date [Time]
     def replace_date_pattern(reference, date)
       copy = reference.dup
 
@@ -122,10 +116,9 @@ class PaymentDocumentService
       copy
     end
 
-    ##
     # Replace the document number elements in the provided pattern with counts from the database
-    # @param reference {string}
-    ##
+    # @param reference [String]
+    # @param date [Time]
     def replace_invoice_number_pattern(reference, date)
       copy = reference.dup
 
diff --git a/app/services/payment_schedule_service.rb b/app/services/payment_schedule_service.rb
index f68dc7f88..b27fd977d 100644
--- a/app/services/payment_schedule_service.rb
+++ b/app/services/payment_schedule_service.rb
@@ -2,14 +2,12 @@
 
 # perform various operations on PaymentSchedules
 class PaymentScheduleService
-  ##
   # Compute a payment schedule for a new subscription to the provided plan
-  # @param plan {Plan}
-  # @param total {Number} Total amount of the current shopping cart (which includes this plan) - without coupon
-  # @param customer {User} the customer
-  # @param coupon {Coupon} apply this coupon, if any
-  # @param start_at {DateTime} schedule the PaymentSchedule to start in the future
-  ##
+  # @param plan [Plan]
+  # @param total [Number] Total amount of the current shopping cart (which includes this plan) - without coupon
+  # @param customer [User] the customer
+  # @param coupon [Coupon] apply this coupon, if any
+  # @param start_at [Time] schedule the PaymentSchedule to start in the future
   def compute(plan, total, customer, coupon: nil, start_at: nil)
     other_items = total - plan.amount
     # base monthly price of the plan
@@ -91,12 +89,10 @@ class PaymentScheduleService
     res
   end
 
-  ##
   # Generate the invoice associated with the given PaymentScheduleItem, with the children elements (InvoiceItems).
-  # @param payment_method {String} the payment method or gateway in use
-  # @param payment_id {String} the identifier of the payment as provided by the payment gateway, in case of card payment
-  # @param payment_type {String} the object type of payment_id
-  ##
+  # @param payment_method [String] the payment method or gateway in use
+  # @param payment_id [String] the identifier of the payment as provided by the payment gateway, in case of card payment
+  # @param payment_type [String] the object type of payment_id
   def generate_invoice(payment_schedule_item, payment_method: nil, payment_id: nil, payment_type: nil)
     # build the base invoice
     invoice = Invoice.new(
@@ -125,12 +121,10 @@ class PaymentScheduleService
     payment_schedule_item.update(invoice_id: invoice.id)
   end
 
-  ##
   # return a paginated list of PaymentSchedule, optionally filtered, with their associated PaymentScheduleItem
-  # @param page {number} page number, used to paginate results
-  # @param size {number} number of items per page
-  # @param filters {Hash} allowed filters: reference, customer, date.
-  ##
+  # @param page [Number] page number, used to paginate results
+  # @param size [Number] number of items per page
+  # @param filters [Hash] allowed filters: reference, customer, date.
   def self.list(page, size, filters = {})
     ps = PaymentSchedule.includes(:operator_profile, :payment_schedule_items, invoicing_profile: [:user])
                         .joins(:invoicing_profile)
diff --git a/app/services/trainings/authorization_service.rb b/app/services/trainings/authorization_service.rb
index 2c6f8d2dd..87bf0866a 100644
--- a/app/services/trainings/authorization_service.rb
+++ b/app/services/trainings/authorization_service.rb
@@ -11,7 +11,7 @@ class Trainings::AuthorizationService
       return unless training.authorization
 
       training.statistic_profile_trainings
-              .where('created_at < ?', DateTime.current - training.authorization_period.months)
+              .where('created_at < ?', Time.current - training.authorization_period.months)
               .find_each do |spt|
         NotificationCenter.call type: 'notify_member_training_authorization_expired',
                                 receiver: spt.statistic_profile.user,
diff --git a/app/services/trainings/auto_cancel_service.rb b/app/services/trainings/auto_cancel_service.rb
index 521ade702..dc6e25f72 100644
--- a/app/services/trainings/auto_cancel_service.rb
+++ b/app/services/trainings/auto_cancel_service.rb
@@ -14,8 +14,8 @@ class Trainings::AutoCancelService
               .includes(slots: :slots_reservations)
               .where(availabilities: { lock: false })
               .where('availabilities.start_at >= ? AND availabilities.start_at <= ?',
-                     DateTime.current,
-                     DateTime.current + training.auto_cancel_deadline.hours)
+                     Time.current,
+                     Time.current + training.auto_cancel_deadline.hours)
               .find_each do |availability|
         next if availability.reservations.count >= training.auto_cancel_threshold
 
@@ -33,7 +33,7 @@ class Trainings::AutoCancelService
                                   attached_object: sr,
                                   meta_data: { auto_refund: auto_refund }
 
-          sr.update(canceled_at: DateTime.current)
+          sr.update(canceled_at: Time.current)
           refund_after_cancel(sr.reservation) if auto_refund
         end
       end
@@ -80,7 +80,7 @@ class Trainings::AutoCancelService
 
       service = WalletService.new(user: reservation.user, wallet: reservation.user.wallet)
       transaction = service.credit(amount)
-      service.create_avoir(transaction, DateTime.current, I18n.t('trainings.refund_for_auto_cancel')) if transaction
+      service.create_avoir(transaction, Time.current, I18n.t('trainings.refund_for_auto_cancel')) if transaction
     end
   end
 end
diff --git a/app/services/trainings/invalidation_service.rb b/app/services/trainings/invalidation_service.rb
index 15daf7347..5b99da30e 100644
--- a/app/services/trainings/invalidation_service.rb
+++ b/app/services/trainings/invalidation_service.rb
@@ -12,7 +12,7 @@ class Trainings::InvalidationService
       return unless training.invalidation
 
       training.statistic_profile_trainings
-              .where('created_at < ?', DateTime.current - training.invalidation_period.months)
+              .where('created_at < ?', Time.current - training.invalidation_period.months)
               .find_each do |spt|
         reservations_since = spt.statistic_profile
                                 .reservations
diff --git a/db/migrate/20160704095606_create_wallets.rb b/db/migrate/20160704095606_create_wallets.rb
index 54c28f583..8c16e5f35 100644
--- a/db/migrate/20160704095606_create_wallets.rb
+++ b/db/migrate/20160704095606_create_wallets.rb
@@ -1,5 +1,6 @@
 # frozen_string_literal:true
 
+# Create Wallets, which are a way to virtually save money for users
 class CreateWallets < ActiveRecord::Migration[4.2]
   def up
     create_table :wallets do |t|
@@ -10,9 +11,9 @@ class CreateWallets < ActiveRecord::Migration[4.2]
     end
 
     # create all wallets
-    execute <<-SQL
+    execute <<-SQL.squish
       INSERT INTO wallets (user_id, amount, created_at, updated_at)
-      SELECT users.id, 0, '#{DateTime.current.iso8601}', '#{DateTime.current.iso8601}'
+      SELECT users.id, 0, '#{Time.current.iso8601}', '#{Time.current.iso8601}'
       FROM users
     SQL
   end
diff --git a/db/migrate/20190606074050_migrate_user_trainings_to_statistic_profile_trainings.rb b/db/migrate/20190606074050_migrate_user_trainings_to_statistic_profile_trainings.rb
index 416d21310..4e2147317 100644
--- a/db/migrate/20190606074050_migrate_user_trainings_to_statistic_profile_trainings.rb
+++ b/db/migrate/20190606074050_migrate_user_trainings_to_statistic_profile_trainings.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal:true
 
+# Due to RGPD regulations, we cannot save trainings after the deletion of the user's account so we migrate those data
+# to the StatisticProfile which is an anonymous ghost of the user's account
 class MigrateUserTrainingsToStatisticProfileTrainings < ActiveRecord::Migration[4.2]
   def up
     user_trainings = execute('SELECT * FROM user_trainings')
@@ -7,14 +9,16 @@ class MigrateUserTrainingsToStatisticProfileTrainings < ActiveRecord::Migration[
     user_trainings.each do |ut|
       user = User.find(ut['user_id'])
       # here we use raw sql to prevent the notify_user callback the email the whole DB
+      # rubocop:disable Rails/SkipsModelValidations
       spt_id = insert("INSERT INTO statistic_profile_trainings (statistic_profile_id, training_id, created_at, updated_at)
-                            VALUES (#{user.statistic_profile.id}, #{ut['training_id']}, '#{ut['created_at']}', '#{DateTime.now.utc}')")
+                            VALUES (#{user.statistic_profile.id}, #{ut['training_id']}, '#{ut['created_at']}', '#{Time.current.utc}')")
+      # rubocop:enable Rails/SkipsModelValidations
 
       # update notifications
       execute("UPDATE notifications SET
                    attached_object_type = 'StatisticProfileTraining',
                    attached_object_id = #{spt_id},
-                   updated_at = '#{DateTime.now.utc}'
+                   updated_at = '#{Time.current.utc}'
                    WHERE attached_object_id = #{ut['id']} AND attached_object_type = 'UserTraining'")
     end
   end
@@ -23,11 +27,11 @@ class MigrateUserTrainingsToStatisticProfileTrainings < ActiveRecord::Migration[
     StatisticProfileTraining.all.each do |spt|
       statistic_profile = StatisticProfile.find(spt.statistic_profile_id)
       ut_id = execute("INSERT INTO user_trainings (user_id, training_id, created_at, updated_at)
-                           VALUES (#{statistic_profile.user_id}, #{spt.training_id}, '#{spt.created_at.utc}', '#{DateTime.now.utc}')")
+                           VALUES (#{statistic_profile.user_id}, #{spt.training_id}, '#{spt.created_at.utc}', '#{Time.current.utc}')")
       execute("UPDATE notifications SET
                    attached_object_type = 'UserTraining',
                    attached_object_id = #{ut_id},
-                   updated_at = '#{DateTime.now.utc}'
+                   updated_at = '#{Time.current.utc}'
                    WHERE attached_object_id = #{spt.id} AND attached_object_type = 'StatisticProfileTraining'")
     end
   end
diff --git a/lib/omni_auth/data_mapping/base.rb b/lib/omni_auth/data_mapping/base.rb
index 7d43c7d07..aa22dda09 100644
--- a/lib/omni_auth/data_mapping/base.rb
+++ b/lib/omni_auth/data_mapping/base.rb
@@ -1,50 +1,49 @@
 # frozen_string_literal: true
 
-# Data mapping functions for SSO authentications (through OmniAuth)
-module OmniAuth::DataMapping
-  # Type-dependant mapping functions
-  module Base
-    extend ActiveSupport::Concern
+# Type-dependant aata mapping functions for SSO authentications (through OmniAuth)
+module OmniAuth::DataMapping::Base
+  extend ActiveSupport::Concern
 
-    included do
-      def local_sym(mapping)
-        (mapping.local_model + '.' + mapping.local_field).to_sym
-      end
+  # rubocop:disable Metrics/BlockLength
+  included do
+    def local_sym(mapping)
+      "#{mapping.local_model}.#{mapping.local_field}".to_sym
+    end
 
-      def map_transformation(transformation, raw_data)
-        value = nil
-        transformation['mapping']&.each do |m|
-          if m['from'] == raw_data
-            value = m['to']
-            break
-          end
+    def map_transformation(transformation, raw_data)
+      value = nil
+      transformation['mapping']&.each do |m|
+        if m['from'] == raw_data
+          value = m['to']
+          break
         end
-        # if no transformation had set any value, return the raw value
-        value || raw_data
       end
+      # if no transformation had set any value, return the raw value
+      value || raw_data
+    end
 
-      def map_boolean(transformation, raw_data)
-        return false if raw_data == transformation['false_value']
+    def map_boolean(transformation, raw_data)
+      return false if raw_data == transformation['false_value']
 
-        true if raw_data == transformation['true_value']
-      end
+      true if raw_data == transformation['true_value']
+    end
 
-      def map_date(transformation, raw_data)
-        case transformation['format']
-        when 'iso8601'
-          DateTime.iso8601(raw_data)
-        when 'rfc2822'
-          DateTime.rfc2822(raw_data)
-        when 'rfc3339'
-          DateTime.rfc3339(raw_data)
-        when 'timestamp-s'
-          DateTime.strptime(raw_data, '%s')
-        when 'timestamp-ms'
-          DateTime.strptime(raw_data, '%Q')
-        else
-          DateTime.parse(raw_data)
-        end
+    def map_date(transformation, raw_data)
+      case transformation['format']
+      when 'iso8601'
+        Time.zone.iso8601(raw_data)
+      when 'rfc2822'
+        Time.rfc2822(raw_data).in_time_zone
+      when 'rfc3339'
+        Time.rfc3339(raw_data).in_time_zone
+      when 'timestamp-s'
+        Time.zone.strptime(raw_data, '%s')
+      when 'timestamp-ms'
+        Time.zone.strptime(raw_data, '%Q')
+      else
+        Time.zone.parse(raw_data)
       end
     end
   end
+  # rubocop:enable Metrics/BlockLength
 end
diff --git a/test/helpers/archive_helper.rb b/test/helpers/archive_helper.rb
index 60f24761d..23ea9c565 100644
--- a/test/helpers/archive_helper.rb
+++ b/test/helpers/archive_helper.rb
@@ -21,7 +21,7 @@ module ArchiveHelper
     archive_json = JSON.parse(archive)
     invoices = Invoice.where(
       'created_at >= :start_date AND created_at <= :end_date',
-      start_date: accounting_period.start_at.to_datetime, end_date: accounting_period.end_at.to_datetime
+      start_date: accounting_period.start_at.to_time.in_time_zone, end_date: accounting_period.end_at.to_time.in_time_zone
     )
 
     assert_equal invoices.count, archive_json['invoices'].count
diff --git a/test/integration/availabilities/as_admin_test.rb b/test/integration/availabilities/as_admin_test.rb
index 374aaed16..891e042fd 100644
--- a/test/integration/availabilities/as_admin_test.rb
+++ b/test/integration/availabilities/as_admin_test.rb
@@ -29,7 +29,7 @@ class Availabilities::AsAdminTest < ActionDispatch::IntegrationTest
     m = Machine.find_by(slug: 'decoupeuse-vinyle')
 
     # this simulates a fullCalendar (v2) call
-    start_date = DateTime.current.utc.strftime('%Y-%m-%d')
+    start_date = Time.current.utc.strftime('%Y-%m-%d')
     end_date = 7.days.from_now.utc.strftime('%Y-%m-%d')
     tz = Time.zone.tzinfo.name
 
@@ -54,7 +54,7 @@ class Availabilities::AsAdminTest < ActionDispatch::IntegrationTest
     Setting.set('spaces_module', false)
 
     # this simulates a fullCalendar (v2) call
-    start_date = DateTime.current.utc.strftime('%Y-%m-%d')
+    start_date = Time.current.utc.strftime('%Y-%m-%d')
     end_date = 7.days.from_now.utc.strftime('%Y-%m-%d')
     tz = Time.zone.tzinfo.name
     get "/api/availabilities?start=#{start_date}&end=#{end_date}&timezone=#{tz}&_=1487169767960&#{all_machines}"
@@ -76,7 +76,7 @@ class Availabilities::AsAdminTest < ActionDispatch::IntegrationTest
 
   test 'get calendar availabilities with spaces' do
     # this simulates a fullCalendar (v2) call
-    start_date = DateTime.current.utc.strftime('%Y-%m-%d')
+    start_date = Time.current.utc.strftime('%Y-%m-%d')
     end_date = 7.days.from_now.utc.strftime('%Y-%m-%d')
     tz = Time.zone.tzinfo.name
     get "/api/availabilities?start=#{start_date}&end=#{end_date}&timezone=#{tz}&_=1487169767960&#{all_spaces}"
@@ -94,7 +94,7 @@ class Availabilities::AsAdminTest < ActionDispatch::IntegrationTest
   end
 
   test 'create availabilities' do
-    date = DateTime.current.change(hour: 8, min: 0, sec: 0)
+    date = Time.current.change(hour: 8, min: 0, sec: 0)
     slots_count = Slot.count
 
     post '/api/availabilities',
@@ -128,15 +128,15 @@ class Availabilities::AsAdminTest < ActionDispatch::IntegrationTest
     assert_not_nil availability[:id], 'availability ID was unexpectedly nil'
 
     # Check the slots
-    assert_equal (availability[:start_at].to_datetime + (availability[:slot_duration].minutes * 4)).iso8601,
+    assert_equal (availability[:start_at].to_time.in_time_zone + (availability[:slot_duration].minutes * 4)).iso8601,
                  availability[:end_at],
                  'expected end_at = start_at + 4 slots of 90 minutes'
     assert_equal (slots_count + (4 * 3)), Slot.count, 'expected (4*3) slots of 90 minutes were created'
     assert_equal 90.minutes, Availability.find(availability[:id]).slots.first.duration
 
     # Check the recurrence
-    assert_equal (availability[:start_at].to_datetime + 2.weeks).to_date,
-                 availability[:end_date].to_datetime.utc.to_date,
+    assert_equal (availability[:start_at].to_time.in_time_zone + 2.weeks).to_date,
+                 availability[:end_date].to_time.in_time_zone.to_date,
                  'expected end_date = start_at + 2 weeks'
   end
 
diff --git a/test/integration/availabilities/as_public_test.rb b/test/integration/availabilities/as_public_test.rb
index cd0ddff7d..c8dd3fd62 100644
--- a/test/integration/availabilities/as_public_test.rb
+++ b/test/integration/availabilities/as_public_test.rb
@@ -4,8 +4,8 @@ require 'test_helper'
 
 class Availabilities::AsPublicTest < ActionDispatch::IntegrationTest
   test 'get public machines availabilities if machines module is active' do
-    start_date = DateTime.current.to_date
-    end_date = (DateTime.current + 7.days).to_date
+    start_date = Time.current.to_date
+    end_date = 7.days.from_now.to_date
 
     get "/api/availabilities/public?start=#{start_date}&end=#{end_date}&timezone=Europe%2FParis&#{all_machines}"
 
@@ -19,15 +19,15 @@ class Availabilities::AsPublicTest < ActionDispatch::IntegrationTest
     availabilities.each_with_index do |a, index|
       assert_not_nil a, "availability #{index} was unexpectedly nil"
       assert_equal 'machines', a[:available_type], "availability #{index} is not a machines availability"
-      assert DateTime.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
-      assert DateTime.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
+      assert Time.zone.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
+      assert Time.zone.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
     end
   end
 
   test 'get anymore machines availabilities if machines module is inactive' do
     Setting.set('machines_module', false)
-    start_date = DateTime.current.to_date
-    end_date = (DateTime.current + 7.days).to_date
+    start_date = Time.current.to_date
+    end_date = 7.days.from_now.to_date
 
     get "/api/availabilities/public?start=#{start_date}&end=#{end_date}&timezone=Europe%2FParis&#{all_machines}"
 
@@ -41,8 +41,8 @@ class Availabilities::AsPublicTest < ActionDispatch::IntegrationTest
   end
 
   test 'get public trainings availabilities' do
-    start_date = DateTime.current.to_date
-    end_date = (DateTime.current + 7.days).to_date
+    start_date = Time.current.to_date
+    end_date = 7.days.from_now.to_date
 
     get "/api/availabilities/public?start=#{start_date}&end=#{end_date}&timezone=Europe%2FParis&#{all_trainings}"
 
@@ -56,14 +56,14 @@ class Availabilities::AsPublicTest < ActionDispatch::IntegrationTest
     availabilities.each_with_index do |a, index|
       assert_not_nil a, "availability #{index} was unexpectedly nil"
       assert_equal 'training', a[:available_type], "availability #{index} is not a training availability"
-      assert DateTime.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
-      assert DateTime.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
+      assert Time.zone.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
+      assert Time.zone.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
     end
   end
 
   test 'get public spaces availabilities' do
-    start_date = DateTime.current.to_date
-    end_date = (DateTime.current + 7.days).to_date
+    start_date = Time.current.to_date
+    end_date = 7.days.from_now.to_date
 
     get "/api/availabilities/public?start=#{start_date}&end=#{end_date}&timezone=Europe%2FParis&#{all_spaces}"
 
@@ -77,8 +77,8 @@ class Availabilities::AsPublicTest < ActionDispatch::IntegrationTest
     availabilities.each_with_index do |a, index|
       assert_not_nil a, "availability #{index} was unexpectedly nil"
       assert_equal 'space', a[:available_type], "availability #{index} is not a space availability"
-      assert DateTime.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
-      assert DateTime.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
+      assert Time.zone.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
+      assert Time.zone.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
     end
   end
 
@@ -98,8 +98,8 @@ class Availabilities::AsPublicTest < ActionDispatch::IntegrationTest
     availabilities.each_with_index do |a, index|
       assert_not_nil a, "availability #{index} was unexpectedly nil"
       assert_equal 'event', a[:available_type], "availability #{index} is not a event availability"
-      assert DateTime.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
-      assert DateTime.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
+      assert Time.zone.parse(a[:start]) > start_date, "availability #{index} starts before the requested period"
+      assert Time.zone.parse(a[:end]) < end_date, "availability #{index} ends after the requested period"
     end
   end
 
diff --git a/test/integration/availabilities/as_user_test.rb b/test/integration/availabilities/as_user_test.rb
index aae9445a2..817198602 100644
--- a/test/integration/availabilities/as_user_test.rb
+++ b/test/integration/availabilities/as_user_test.rb
@@ -12,7 +12,7 @@ class Availabilities::AsUserTest < ActionDispatch::IntegrationTest
     m = Machine.find_by(slug: 'decoupeuse-vinyle')
 
     # this simulates a fullCalendar (v2) call
-    start_date = DateTime.current.utc.strftime('%Y-%m-%d')
+    start_date = Time.current.utc.strftime('%Y-%m-%d')
     end_date = 7.days.from_now.utc.strftime('%Y-%m-%d')
     tz = Time.zone.tzinfo.name
 
@@ -29,13 +29,10 @@ class Availabilities::AsUserTest < ActionDispatch::IntegrationTest
     assert_not_nil availabilities[0][:machine], "first availability's machine was unexpectedly nil"
     assert_equal m.id, availabilities[0][:machine][:id], "first availability's machine does not match the required machine"
 
-    # Check that we din't get availabilities from the past
-    availabilities.each do |a|
-      assert_not a[:start] < DateTime.current, 'retrieved a slot in the past'
-    end
-
-    # Check that we don't get availabilities in more than a month
     availabilities.each do |a|
+      # Check that we din't get availabilities from the past
+      assert_not a[:start] < Time.current, 'retrieved a slot in the past'
+      # Check that we don't get availabilities in more than a month
       assert_not a[:start] > 1.month.from_now, 'retrieved a slot in more than 1 month for user who has no yearly subscription'
     end
   end
diff --git a/test/integration/open_api/accounting_test.rb b/test/integration/open_api/accounting_test.rb
index 60f677abb..9feca27af 100644
--- a/test/integration/open_api/accounting_test.rb
+++ b/test/integration/open_api/accounting_test.rb
@@ -54,7 +54,7 @@ class OpenApi::AccountingTest < ActionDispatch::IntegrationTest
     lines = json_response(response.body)
     assert lines[:lines].count.positive?
     assert(lines[:lines].all? do |line|
-      date = DateTime.parse(line[:date])
+      date = Time.zone.parse(line[:date])
       date >= '2022-09-01'.to_date && date <= '2022-09-30'.to_date
     end)
   end
diff --git a/test/integration/open_api/users_test.rb b/test/integration/open_api/users_test.rb
index a16848634..3cf57c30f 100644
--- a/test/integration/open_api/users_test.rb
+++ b/test/integration/open_api/users_test.rb
@@ -81,6 +81,6 @@ class OpenApi::UsersTest < ActionDispatch::IntegrationTest
 
     users = json_response(response.body)
     assert users[:users].count.positive?
-    assert(users[:users].all? { |u| DateTime.parse(u[:created_at]) >= DateTime.parse('2018-01-01T00:00:00+01:00') })
+    assert(users[:users].all? { |u| Time.zone.parse(u[:created_at]) >= Time.zone.parse('2018-01-01T00:00:00+01:00') })
   end
 end
diff --git a/test/integration/reservations/space_seats_test.rb b/test/integration/reservations/space_seats_test.rb
index 75f330c5b..5370e4b9a 100644
--- a/test/integration/reservations/space_seats_test.rb
+++ b/test/integration/reservations/space_seats_test.rb
@@ -17,7 +17,7 @@ class Reservations::SpaceSeatsTest < ActionDispatch::IntegrationTest
 
     space = Space.first
 
-    date = (DateTime.current + 1.day).change(hour: 8, min: 0, sec: 0)
+    date = 1.day.from_now.change(hour: 8, min: 0, sec: 0)
 
     post '/api/availabilities',
          params: {
diff --git a/test/models/coupon_test.rb b/test/models/coupon_test.rb
index 6f7efa052..701afdc25 100644
--- a/test/models/coupon_test.rb
+++ b/test/models/coupon_test.rb
@@ -1,16 +1,18 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class CouponTest < ActiveSupport::TestCase
-
   test 'valid coupon with percentage' do
-    c = Coupon.new({name: 'Hot deals', code: 'HOT15', percent_off: 15, validity_per_user: 'once', valid_until: (DateTime.current + 2.weeks), max_usages: 100, active: true})
+    c = Coupon.new({ name: 'Hot deals', code: 'HOT15', percent_off: 15, validity_per_user: 'once', valid_until: 2.weeks.from_now,
+                     max_usages: 100, active: true })
     assert c.valid?
     assert_equal 'active', c.status, 'Invalid coupon status'
     assert_equal 'percent_off', c.type, 'Invalid coupon type'
   end
 
   test 'coupon must have a valid percentage' do
-    c = Coupon.new({name: 'Amazing deal', code: 'DISCOUNT', percent_off: 200, validity_per_user: 'once'})
+    c = Coupon.new({ name: 'Amazing deal', code: 'DISCOUNT', percent_off: 200, validity_per_user: 'once' })
     assert c.invalid?
   end
 
@@ -20,19 +22,19 @@ class CouponTest < ActiveSupport::TestCase
   end
 
   test 'two coupons cannot have the same code' do
-    c = Coupon.new({name: 'Summer deals', code: 'SUNNYFABLAB', percent_off: 15, validity_per_user: 'always'})
+    c = Coupon.new({ name: 'Summer deals', code: 'SUNNYFABLAB', percent_off: 15, validity_per_user: 'always' })
     assert c.invalid?
   end
 
   test 'valid coupon with cash amount' do
-    c = Coupon.new({name: 'Essential Box', code: 'KWXX2M', amount_off: 2000, validity_per_user: 'once', max_usages: 1, active: true})
+    c = Coupon.new({ name: 'Essential Box', code: 'KWXX2M', amount_off: 2000, validity_per_user: 'once', max_usages: 1, active: true })
     assert c.valid?
     assert_equal 'active', c.status, 'Invalid coupon status'
     assert_equal 'amount_off', c.type, 'Invalid coupon type'
   end
 
   test 'coupon with cash amount cannot be used with cheaper cart' do
-    c = Coupon.new({name: 'Premium Box', code: '6DDX2T44MQ', amount_off: 20000, validity_per_user: 'once', max_usages: 1, active: true})
+    c = Coupon.new({ name: 'Premium Box', code: '6DDX2T44MQ', amount_off: 20_000, validity_per_user: 'once', max_usages: 1, active: true })
     assert_equal 'amount_exceeded', c.status(User.find_by(username: 'jdupond').id, 2000)
   end
 end
diff --git a/test/services/prepaid_pack_service_test.rb b/test/services/prepaid_pack_service_test.rb
index 221ed90b3..44953b343 100644
--- a/test/services/prepaid_pack_service_test.rb
+++ b/test/services/prepaid_pack_service_test.rb
@@ -25,7 +25,7 @@ class PrepaidPackServiceTest < ActiveSupport::TestCase
   test 'update user pack minutes' do
     availabilities_service = Availabilities::AvailabilitiesService.new(@acamus)
 
-    slots = availabilities_service.machines([@machine], @acamus, { start: DateTime.now, end: 1.day.from_now })
+    slots = availabilities_service.machines([@machine], @acamus, { start: Time.current, end: 1.day.from_now })
     reservation = Reservation.create(
       reservable_id: @machine.id,
       reservable_type: Machine.name,