Avoid DateTime usage

.rubocop.yml

     - 'app/mailers/participant_mailer.rb'
     - 'db/seeds.rb'
 
-# Offense count: 8
-# Configuration parameters: AllowCoercion.
-Style/DateTime:
-  Exclude:
-    - 'app/controllers/api/groups_controller.rb'
-    - 'app/controllers/authentication_controller.rb'
-    - 'app/controllers/dashboard_controller.rb'
-    - 'app/helpers/authentication_helper.rb'
-    - 'app/models/group.rb'
-    - 'db/seeds.rb'
-
 # Offense count: 55
 Style/Documentation:
   Enabled: false

app/controllers/api/groups_controller.rb

       return unless input
 
       begin
-        DateTime.parse input
+        DateTime.parse input # rubocop:disable Style/DateTime
       rescue ArgumentError
         nil
       end

app/controllers/authentication_controller.rb

       redirect_to action: 'login'
       return false
     end
-    if token.expires && (token.expires < DateTime.now)
+
+    if token.expires&.past?
       flash_message(:warning, I18n.t('authentication.token_expired'))
       redirect_to action: 'login'
       return false

app/controllers/dashboard_controller.rb

     @upcoming = current_person
                 .participants
                 .joins(:activity)
-                .where('activities.end >= ? OR (activities.end IS NULL AND activities.start >= ?)', DateTime.now, DateTime.now)
+                .where('activities.end >= ? OR (activities.end IS NULL AND activities.start >= ?)', Time.now, Time.now)
                 .order('activities.start ASC')
     @user_organized = @upcoming
                       .where(is_organizer: true)

app/helpers/authentication_helper.rb

   def logged_in?
     # Case 1: User has an active session inside the cookie.
     # We verify that the session hasn't expired yet.
-    if session[:user_id] && session[:expires].to_time > DateTime.now
+    if session[:user_id] && session[:expires].to_time.future?
 
       user_session
 
-      return false if !@user_session.active || @user_session.expires < Time.now
+      return false if !@user_session.active || @user_session.expires.past?
 
       true
 
 
         session_password = BCrypt::Password.new @user_session.remember_digest
 
-        if @user_session.expires > DateTime.now &&
+        if @user_session.expires.future? &&
            session_password == cookies.signed.permanent[:remember_token]
           log_in @user_session.user, false, false
           return true

app/models/group.rb

 
   # @return [Array<Activity>] the activities that haven't started yet.
   def future_activities
-    self.activities.where('start > ?', DateTime.now)
+    self.activities.where('start > ?', Time.now)
   end
 
   # @return [Array<Activity>]

db/seeds.rb

 
 Group.all.each do |g|
   10.times do
-    starttime = Faker::Time.between(DateTime.now, 1.years.since, :morning)
+    starttime = Faker::Time.between(Time.now, 1.years.since, :morning)
     endtime   = Faker::Time.between(1.hours.since(starttime), 1.days.since(starttime), :afternoon)
     deadline  = 5.days.ago(starttime)