Merge pull request #10851 from opf/implementation/41821-non-working-days-and-duration-in-scheduling

[#41821] Non working days & duration in scheduling

.rubocop.yml

@@ -124,6 +124,9 @@ Naming/PredicateName:
   ForbiddenPrefixes:
     - is_
 
+Naming/VariableNumber:
+  AllowedPatterns:
+    - '\w_20\d\d' # allow dates like christmas_2022 or date_2034_04_12
 
 # There are valid cases in which to use methods like:
 # * update_all
@@ -207,6 +210,7 @@ RSpec/NamedSubject:
 RSpec/ContextWording:
   Prefixes:
     - as
+    - 'on'
     - when
     - with
     - without

app/services/work_packages/schedule_dependency/dependency.rb

@@ -51,9 +51,10 @@ class WorkPackages::ScheduleDependency::Dependency
   end
 
   def soonest_start_date
-    follows_relations
+    soonest_start = follows_relations
       .filter_map(&:successor_soonest_start)
       .max
+    WorkPackages::Shared::Days.for(work_package).soonest_working_day(soonest_start)
   end
 
   def start_date

app/services/work_packages/set_attributes_service.rb

@@ -182,11 +182,7 @@ class WorkPackages::SetAttributesService < ::BaseServices::SetAttributes
   def update_duration
     return unless date_changed_but_not_duration?
 
-    work_package.duration = if work_package.start_date && work_package.due_date
-                              work_package.due_date - work_package.start_date + 1
-                            else
-                              1
-                            end
+    work_package.duration = WorkPackages::Shared::Days.for(work_package).duration(work_package.start_date, work_package.due_date)
   end
 
   def set_version_to_nil

app/services/work_packages/set_schedule_service.rb

@@ -56,11 +56,23 @@ class WorkPackages::SetScheduleService
 
   private
 
+  # rubocop:disable Metrics/AbcSize
   def schedule_by_parent
     work_packages
       .select { |wp| wp.start_date.nil? && wp.parent }
-      .each { |wp| wp.start_date = wp.parent.soonest_start }
+      .each do |wp|
+        days = WorkPackages::Shared::Days.for(wp)
+        wp.start_date = days.soonest_working_day(wp.parent.soonest_start)
+        if wp.due_date || wp.duration
+          wp.due_date = [
+            wp.start_date,
+            days.due_date(wp.start_date, wp.duration),
+            wp.due_date
+          ].compact.max
+        end
+      end
   end
+  # rubocop:enable Metrics/AbcSize
 
   # Finds all work packages that need to be rescheduled because of a
   # rescheduling of the service's work package and reschedules them.
@@ -137,45 +149,61 @@ class WorkPackages::SetScheduleService
     elsif !scheduled.start_date && min_start_date
       schedule_on_missing_dates(scheduled, min_start_date)
     elsif !delta.zero?
-      reschedule_by_delta(scheduled, delta, min_start_date)
+      reschedule_by_delta(scheduled, delta, min_start_date, dependency)
     end
   end
 
   def reschedule_to_date(scheduled, date)
     new_start_date = [scheduled.start_date, date].compact.max
-    set_dates(scheduled,
-              new_start_date,
-              (scheduled.due_date && !scheduled.duration.nil?) && (new_start_date + scheduled.duration - 1))
-  end
-
-  def reschedule_by_delta(scheduled, delta, min_start_date)
-    required_delta = [min_start_date - (scheduled.start_date || min_start_date), [delta, 0].min].max
+    # a new due date is set only if the moving work package already has one
+    if scheduled.due_date
+      new_due_date = [
+        WorkPackages::Shared::Days.for(scheduled).due_date(new_start_date, scheduled.duration),
+        new_start_date,
+        scheduled.due_date
+      ].compact.max
+    end
 
-    scheduled.start_date += required_delta
-    scheduled.due_date += required_delta if scheduled.due_date
+    set_dates(scheduled, new_start_date, new_due_date)
   end
 
-  # If the start_date of scheduled is nil at this point something
-  # went wrong before. So we fix it now by setting the date.
   def schedule_on_missing_dates(scheduled, min_start_date)
+    min_start_date = WorkPackages::Shared::Days.for(scheduled).soonest_working_day(min_start_date)
     set_dates(scheduled,
               min_start_date,
               scheduled.due_date && scheduled.due_date < min_start_date ? min_start_date : scheduled.due_date)
   end
 
+  def reschedule_by_delta(scheduled, moved_delta, min_start_date, dependency)
+    days = WorkPackages::Shared::Days.for(dependency.work_package)
+
+    # TODO: can it be moved to dependency?
+    min_start_delta = days.delta(previous: scheduled.start_date || min_start_date, current: min_start_date)
+    required_delta = [min_start_delta, [moved_delta, 0].min].max
+
+    scheduled_days = WorkPackages::Shared::Days.for(scheduled)
+    new_start_date = scheduled_days.add_days(scheduled.start_date, required_delta)
+    new_due_date = scheduled_days.add_days(scheduled.due_date, required_delta) if scheduled.due_date
+    scheduled.start_date = new_start_date
+    scheduled.due_date = new_due_date
+  end
+
   def follows_delta(dependency)
     if dependency.moving_predecessors.any?
-      date_rescheduling_delta(dependency.moving_predecessors.first)
+      date_rescheduling_delta(dependency.moving_predecessors.first, dependency.work_package)
     else
       0
     end
   end
 
-  def date_rescheduling_delta(predecessor)
+  def date_rescheduling_delta(predecessor, follower)
+    days = WorkPackages::Shared::Days.for(follower)
     if predecessor.due_date.present?
-      predecessor.due_date - (predecessor.due_date_before_last_save || predecessor.due_date_was || predecessor.due_date)
+      previous_due_date = predecessor.due_date_before_last_save || predecessor.due_date_was || predecessor.due_date
+      days.delta(previous: previous_due_date, current: predecessor.due_date)
     elsif predecessor.start_date.present?
-      predecessor.start_date - (predecessor.start_date_before_last_save || predecessor.start_date_was || predecessor.start_date)
+      previous_start_date = predecessor.start_date_before_last_save || predecessor.start_date_was || predecessor.start_date
+      days.delta(previous: previous_start_date, current: predecessor.start_date)
     else
       0
     end
@@ -184,11 +212,8 @@ class WorkPackages::SetScheduleService
   def set_dates(work_package, start_date, due_date)
     work_package.start_date = start_date
     work_package.due_date = due_date
-    work_package.duration = if start_date && due_date
-                              due_date - start_date + 1
-                            else
-                              # This needs to change to nil once duration can be set
-                              1
-                            end
+    work_package.duration = WorkPackages::Shared::Days
+                              .for(work_package)
+                              .duration(start_date, due_date)
   end
 end

app/services/work_packages/shared/all_days.rb

@@ -0,0 +1,69 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module WorkPackages
+  module Shared
+    class AllDays
+      # Returns number of days between two dates, inclusive.
+      def duration(start_date, due_date)
+        return no_duration if start_date.nil? || due_date.nil?
+
+        (start_date..due_date).count
+      end
+
+      def due_date(start_date, duration)
+        return nil unless start_date && duration
+        raise ArgumentError, 'duration must be strictly positive' if duration.is_a?(Integer) && duration <= 0
+
+        start_date + duration - 1
+      end
+
+      def add_days(date, count)
+        date + count.days
+      end
+
+      def soonest_working_day(date)
+        date
+      end
+
+      def delta(previous:, current:)
+        current - previous
+      end
+
+      def working?(_date)
+        true
+      end
+
+      private
+
+      def no_duration
+        OpenProject::FeatureDecisions.work_packages_duration_field_active? ? nil : 1
+      end
+    end
+  end
+end

app/services/work_packages/shared/days.rb

@@ -0,0 +1,40 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module WorkPackages
+  module Shared
+    class Days
+      # Returns the right day computation instance for the given instance.
+      def self.for(work_package)
+        return AllDays.new unless OpenProject::FeatureDecisions.work_packages_duration_field_active?
+
+        work_package.ignore_non_working_days ? AllDays.new : WorkingDays.new
+      end
+    end
+  end
+end

app/services/work_packages/shared/working_days.rb

@@ -0,0 +1,129 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module WorkPackages
+  module Shared
+    class WorkingDays
+      # Returns number of working days between two dates, excluding weekend days
+      # and non working days.
+      def duration(start_date, due_date)
+        return no_duration unless start_date && due_date
+
+        (start_date..due_date).count { working?(_1) }
+      end
+
+      def due_date(start_date, duration)
+        return nil unless start_date && duration
+        raise ArgumentError, 'duration must be strictly positive' if duration.is_a?(Integer) && duration <= 0
+
+        due_date = start_date
+        until duration <= 1 && working?(due_date)
+          due_date += 1
+          duration -= 1 if working?(due_date)
+        end
+        due_date
+      end
+
+      def add_days(date, count)
+        while count > 0
+          date += 1
+          count -= 1 if working?(date)
+        end
+        while count < 0
+          date -= 1
+          count += 1 if working?(date)
+        end
+        date
+      end
+
+      def soonest_working_day(date)
+        return unless date
+
+        until working?(date)
+          date += 1
+        end
+        date
+      end
+
+      def delta(previous:, current:)
+        delta = 0
+        direction = previous < current ? 1 : -1
+        pos = last_pos = previous
+        while pos != current
+          pos += direction
+          if working?(last_pos) && working?(pos)
+            delta += direction
+            last_pos = pos
+          end
+        end
+        delta
+      end
+
+      def working?(date)
+        working_week_day?(date) && working_specific_date?(date)
+      end
+
+      private
+
+      def no_duration
+        OpenProject::FeatureDecisions.work_packages_duration_field_active? ? nil : 1
+      end
+
+      def working_week_day?(date)
+        working_week_days[date.wday]
+      end
+
+      def working_specific_date?(date)
+        non_working_dates.exclude?(date)
+      end
+
+      def working_week_days
+        return @working_week_days if defined?(@working_week_days)
+
+        # WeekDay day of the week is stored as ISO, meaning Sunday is 7.
+        # Ruby Date#wday value for Sunday is 0.
+        # To make both work, an array of 8 elements is created
+        # where array[0] = array[7] = value for Sunday
+        #
+        # Because the database table for WeekDay could be empty or incomplete
+        # (like in tests), the initial array is built with all days considered
+        # working (value is `true`)
+        @working_week_days = [true] * 8
+        WeekDay.pluck(:day, :working).each do |day, working|
+          @working_week_days[day] = working
+        end
+        @working_week_days[0] = @working_week_days[7] # value for Sunday is present at index 0 AND index 7
+        @working_week_days
+      end
+
+      def non_working_dates
+        @non_working_dates ||= Set.new(NonWorkingDay.pluck(:date))
+      end
+    end
+  end
+end

spec/factories/work_package_factory.rb

@@ -40,14 +40,7 @@ FactoryBot.define do
     author factory: :user
     created_at { Time.zone.now }
     updated_at { Time.zone.now }
-    duration do
-      if start_date && due_date
-        due_date - start_date + 1
-      else
-        # This needs to change to nil once duration can be set
-        1
-      end
-    end
+    duration { WorkPackages::Shared::Days.for(self).duration(start_date&.to_date, due_date&.to_date) }
 
     callback(:after_build) do |work_package, evaluator|
       work_package.type = work_package.project.types.first unless work_package.type

spec/features/work_packages/table/duration_field_spec.rb

@@ -5,11 +5,12 @@ describe 'Duration field in the work package table',
          js: true do
   shared_let(:current_user) { create :admin }
   shared_let(:work_package) do
+    next_monday = Time.zone.today.beginning_of_week.next_occurring(:monday)
     create :work_package,
            subject: 'moved',
            author: current_user,
-           start_date: Time.zone.today.beginning_of_week.next_occurring(:monday),
-           due_date: Time.zone.today.beginning_of_week.next_occurring(:thursday)
+           start_date: next_monday,
+           due_date: next_monday.next_occurring(:thursday)
   end
 
   let!(:wp_table) { Pages::WorkPackagesTable.new(work_package.project) }
@@ -33,6 +34,6 @@ describe 'Duration field in the work package table',
   end
 
   it 'shows the duration as days' do
-    duration.expect_state_text '3 days'
+    duration.expect_state_text '4 days'
   end
 end

spec/models/mail_handler_spec.rb

@@ -794,7 +794,7 @@ describe MailHandler, type: :model do
               "status_id" => [original_status.id, resolved_status.id],
               "assigned_to_id" => [nil, other_user.id],
               "start_date" => [nil, Date.parse("Fri, 01 Jan 2010")],
-              "duration" => [1, 365],
+              "duration" => [nil, 365],
               "custom_fields_#{float_cf.id}" => [nil, "52.6"]
             )
         end

spec/services/work_packages/schedule_dependency/dependency_spec.rb

@@ -59,8 +59,8 @@ RSpec.describe WorkPackages::ScheduleDependency::Dependency do
     end
   end
 
-  def create_follower_of(work_package)
-    create(:work_package, subject: "follower of #{work_package.subject}").tap do |follower|
+  def create_follower_of(work_package, **attributes)
+    create(:work_package, subject: "follower of #{work_package.subject}", **attributes).tap do |follower|
       create(:follows_relation, from: follower, to: work_package)
     end
   end
@@ -232,5 +232,14 @@ RSpec.describe WorkPackages::ScheduleDependency::Dependency do
         expect(dependency_for(follower).soonest_start_date).to eq(unmoved_follower_predecessor.due_date + 1.day)
       end
     end
+
+    context 'with non working days', with_flag: { work_packages_duration_field_active: true } do
+      let!(:tomorrow_we_do_not_work!) { create(:non_working_day, date: Time.zone.tomorrow) }
+
+      it 'returns the soonest start date being a working day' do
+        follower = create_follower_of(work_package, ignore_non_working_days: false)
+        expect(dependency_for(follower).soonest_start_date).to eq(work_package.due_date + 2.days)
+      end
+    end
   end
 end

spec/services/work_packages/set_schedule_service_spec.rb

@@ -109,11 +109,12 @@ describe WorkPackages::SetScheduleService do
     work_package
   end
 
-  def create_follower_child(parent, start, due)
-    create_follower(start,
-                    due,
-                    {},
-                    parent:)
+  def create_child(parent, start_date, due_date)
+    create(:work_package,
+           subject: "child of #{parent.subject}",
+           start_date:,
+           due_date:,
+           parent:)
   end
 
   subject { instance.call(attributes) }
@@ -142,12 +143,7 @@ describe WorkPackages::SetScheduleService do
           .to eql(due_date),
               "Expected work package ##{wp.id} '#{wp.subject}' to have due date #{due_date}, got #{result.due_date}"
 
-        duration = if start_date && due_date
-                     (due_date - start_date + 1).to_i
-                   else
-                     # This needs to change to nil once duration can be set
-                     1
-                   end
+        duration = WorkPackages::Shared::AllDays.new.duration(start_date, due_date)
 
         expect(result.duration)
           .to eql(duration),
@@ -694,7 +690,7 @@ describe WorkPackages::SetScheduleService do
     let(:child_start_date) { follower1_start_date }
     let(:child_due_date) { follower1_due_date }
 
-    let(:child_work_package) { create_follower_child(following_work_package1, child_start_date, child_due_date) }
+    let(:child_work_package) { create_child(following_work_package1, child_start_date, child_due_date) }
 
     let!(:following) do
       [following_work_package1,
@@ -723,8 +719,8 @@ describe WorkPackages::SetScheduleService do
     let(:child2_start_date) { follower1_start_date + 8.days }
     let(:child2_due_date) { follower1_due_date }
 
-    let(:child1_work_package) { create_follower_child(following_work_package1, child1_start_date, child1_due_date) }
-    let(:child2_work_package) { create_follower_child(following_work_package1, child2_start_date, child2_due_date) }
+    let(:child1_work_package) { create_child(following_work_package1, child1_start_date, child1_due_date) }
+    let(:child2_work_package) { create_child(following_work_package1, child2_start_date, child2_due_date) }
 
     let!(:following) do
       [following_work_package1,
@@ -923,13 +919,22 @@ describe WorkPackages::SetScheduleService do
               .and_return(new_parent_work_package)
     end
 
-    context "with the parent being restricted in it's ability to be moved" do
+    context "with the parent being restricted in its ability to be moved" do
       let(:soonest_date) { Time.zone.today + 3.days }
 
-      it 'sets the start date to the earliest possible date' do
+      it 'sets the start date and due date to the earliest possible date' do
         subject
 
         expect(work_package.start_date).to eql(Time.zone.today + 3.days)
+        expect(work_package.due_date).to eql(Time.zone.today + 3.days)
+      end
+
+      it 'does not change the due date if after the newly set start date' do
+        work_package.due_date = Time.zone.today + 5.days
+        subject
+
+        expect(work_package.start_date).to eql(Time.zone.today + 3.days)
+        expect(work_package.due_date).to eql(Time.zone.today + 5.days)
       end
     end
 

spec/services/work_packages/shared/all_days_spec.rb

@@ -0,0 +1,185 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'rails_helper'
+require_relative 'shared_examples_days'
+
+RSpec.describe WorkPackages::Shared::AllDays do
+  subject { described_class.new }
+
+  sunday_2022_07_31 = Date.new(2022, 7, 31)
+
+  describe '#duration' do
+    context 'without any week days created' do
+      it 'considers all days as working days and returns the number of days between two dates, inclusive' do
+        expect(subject.duration(sunday_2022_07_31, sunday_2022_07_31 + 6)).to eq(7)
+        expect(subject.duration(sunday_2022_07_31, sunday_2022_07_31 + 50)).to eq(51)
+      end
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      it 'considers all days as working days and returns the number of days between two dates, inclusive' do
+        expect(subject.duration(sunday_2022_07_31, sunday_2022_07_31 + 6)).to eq(7)
+        expect(subject.duration(sunday_2022_07_31, sunday_2022_07_31 + 50)).to eq(51)
+      end
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      include_examples 'it returns duration', 365, Date.new(2022, 1, 1), Date.new(2022, 12, 31)
+      include_examples 'it returns duration', 365 * 2, Date.new(2022, 1, 1), Date.new(2023, 12, 31)
+    end
+
+    context 'without start date', with_flag: { work_packages_duration_field_active: true } do
+      it 'returns nil' do
+        expect(subject.duration(nil, sunday_2022_07_31)).to be_nil
+      end
+
+      context 'when work packages duration field is inactive', with_flag: { work_packages_duration_field_active: false } do
+        it 'returns 1' do
+          expect(subject.duration(nil, sunday_2022_07_31)).to eq(1)
+        end
+      end
+    end
+
+    context 'without due date', with_flag: { work_packages_duration_field_active: true } do
+      it 'returns nil' do
+        expect(subject.duration(sunday_2022_07_31, nil)).to be_nil
+      end
+
+      context 'when work packages duration field is inactive', with_flag: { work_packages_duration_field_active: false } do
+        it 'returns 1' do
+          expect(subject.duration(sunday_2022_07_31, nil)).to eq(1)
+        end
+      end
+    end
+  end
+
+  describe '#due_date' do
+    it 'returns the due date for a start date and a duration' do
+      expect(subject.due_date(sunday_2022_07_31, 1)).to eq(sunday_2022_07_31)
+      expect(subject.due_date(sunday_2022_07_31, 10)).to eq(sunday_2022_07_31 + 9.days)
+    end
+
+    it 'raises an error if duration is 0 or negative' do
+      expect { subject.due_date(sunday_2022_07_31, 0) }
+        .to raise_error ArgumentError, 'duration must be strictly positive'
+      expect { subject.due_date(sunday_2022_07_31, -10) }
+        .to raise_error ArgumentError, 'duration must be strictly positive'
+    end
+
+    it 'returns nil if start_date is nil' do
+      expect(subject.due_date(nil, 1)).to be_nil
+    end
+
+    it 'returns nil if duration is nil' do
+      expect(subject.due_date(sunday_2022_07_31, nil)).to be_nil
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      include_examples 'due_date', start_date: sunday_2022_07_31, duration: 1, expected: sunday_2022_07_31
+      include_examples 'due_date', start_date: sunday_2022_07_31, duration: 5, expected: sunday_2022_07_31 + 4.days
+      include_examples 'due_date', start_date: sunday_2022_07_31, duration: 10, expected: sunday_2022_07_31 + 9.days
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      include_examples 'due_date', start_date: Date.new(2022, 1, 1), duration: 365, expected: Date.new(2022, 12, 31)
+      include_examples 'due_date', start_date: Date.new(2022, 1, 1), duration: 365 * 2, expected: Date.new(2023, 12, 31)
+    end
+  end
+
+  describe '#add_days' do
+    it 'adds the number of days to the date' do
+      expect(subject.add_days(sunday_2022_07_31, 7)).to eq(Date.new(2022, 8, 7))
+    end
+
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: 0, expected: Date.new(2022, 6, 15)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: 1, expected: Date.new(2022, 6, 16)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: 10, expected: Date.new(2022, 6, 25)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: 100, expected: Date.new(2022, 9, 23)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: 365, expected: Date.new(2023, 6, 15)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: -1, expected: Date.new(2022, 6, 14)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: -10, expected: Date.new(2022, 6, 5)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: -100, expected: Date.new(2022, 3, 7)
+    include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: -730, expected: Date.new(2020, 6, 15)
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      it 'adds the number of days to the date' do
+        expect(subject.add_days(sunday_2022_07_31, 7)).to eq(Date.new(2022, 8, 7))
+        expect(subject.add_days(sunday_2022_07_31, -7)).to eq(Date.new(2022, 7, 24))
+      end
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      it 'adds the number of days to the date' do
+        expect(subject.add_days(Date.new(2022, 1, 1), 365)).to eq(Date.new(2023, 1, 1))
+        expect(subject.add_days(Date.new(2022, 1, 1), -365)).to eq(Date.new(2021, 1, 1))
+      end
+    end
+  end
+
+  describe '#soonest_working_day' do
+    it 'returns the given day' do
+      expect(subject.soonest_working_day(sunday_2022_07_31)).to eq(sunday_2022_07_31)
+    end
+
+    it 'returns nil if given date is nil' do
+      expect(subject.soonest_working_day(nil)).to be_nil
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      it 'returns the given day' do
+        expect(subject.soonest_working_day(sunday_2022_07_31)).to eq(sunday_2022_07_31)
+      end
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      it 'returns the given day' do
+        expect(subject.soonest_working_day(Date.new(2022, 12, 25))).to eq(Date.new(2022, 12, 25))
+      end
+    end
+  end
+
+  describe '#delta' do
+    it 'returns the number of shift from one day to another between two dates' do
+      expect(subject.delta(previous: Date.new(2022, 8, 1), current: Date.new(2022, 8, 30))).to eq(29)
+      expect(subject.delta(previous: Date.new(2022, 8, 15), current: Date.new(2022, 8, 1))).to eq(-14)
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      it 'returns the same delta as without them' do
+        expect(subject.delta(previous: Date.new(2022, 8, 1), current: Date.new(2022, 8, 30))).to eq(29)
+      end
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      it 'returns the same delta as without them' do
+        expect(subject.delta(previous: Date.new(2022, 12, 1), current: Date.new(2023, 1, 1))).to eq(31)
+      end
+    end
+  end
+end

spec/services/work_packages/shared/days_spec.rb

@@ -0,0 +1,64 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'rails_helper'
+
+RSpec.describe WorkPackages::Shared::Days do
+  subject { described_class.new }
+
+  describe '.for', with_flag: { work_packages_duration_field_active: true } do
+    context 'for a work_package ignoring non working days' do
+      let(:work_package) { build_stubbed(:work_package, ignore_non_working_days: true) }
+
+      it 'returns an AllDays instance' do
+        expect(described_class.for(work_package)).to be_an_instance_of(WorkPackages::Shared::AllDays)
+      end
+    end
+
+    context 'for a work_package respecting non working days' do
+      let(:work_package) { build_stubbed(:work_package, ignore_non_working_days: false) }
+
+      it 'returns a WorkingDays instance' do
+        expect(described_class.for(work_package)).to be_an_instance_of(WorkPackages::Shared::WorkingDays)
+      end
+    end
+
+    context 'when work packages duration field is inactive', with_flag: { work_packages_duration_field_active: false } do
+      it 'always returns an AllDays instance' do
+        work_package = build_stubbed(:work_package)
+        expect(described_class.for(work_package)).to be_an_instance_of(WorkPackages::Shared::AllDays)
+
+        work_package = build_stubbed(:work_package, ignore_non_working_days: true)
+        expect(described_class.for(work_package)).to be_an_instance_of(WorkPackages::Shared::AllDays)
+
+        work_package = build_stubbed(:work_package, ignore_non_working_days: false)
+        expect(described_class.for(work_package)).to be_an_instance_of(WorkPackages::Shared::AllDays)
+      end
+    end
+  end
+end

spec/services/work_packages/shared/shared_examples_days.rb

@@ -0,0 +1,85 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+Date::DATE_FORMATS[:wday_date] = '%a %-d %b %Y' # Fri 5 Aug 2022
+
+RSpec.shared_context 'with weekend days Saturday and Sunday' do
+  shared_let(:week_days) { create(:week_days) }
+end
+
+RSpec.shared_context 'with non working days Christmas 2022 and new year 2023' do
+  shared_let(:christmas) { create(:non_working_day, date: Date.new(2022, 12, 25)) }
+  shared_let(:new_year_day) { create(:non_working_day, date: Date.new(2023, 1, 1)) }
+end
+
+RSpec.configure do |rspec|
+  rspec.include_context 'with weekend days Saturday and Sunday', :weekend_saturday_sunday
+  rspec.include_context 'with non working days Christmas 2022 and new year 2023', :christmas_2022_new_year_2023
+end
+
+RSpec.shared_examples 'it returns duration' do |expected_duration, start_date, due_date|
+  from_date_format = '%a %-d'
+  from_date_format += ' %b' if [start_date.month, start_date.year] != [due_date.month, due_date.year]
+  from_date_format += ' %Y' if start_date.year != due_date.year
+
+  it "from #{start_date.strftime(from_date_format)} " \
+     "to #{due_date.to_fs(:wday_date)} " \
+     "=> #{expected_duration}" \
+  do
+    expect(subject.duration(start_date, due_date)).to eq(expected_duration)
+  end
+end
+
+RSpec.shared_examples 'due_date' do |start_date:, duration:, expected:|
+  it "due_date(#{start_date.to_fs(:wday_date)}, #{duration}) => #{expected.to_fs(:wday_date)}" do
+    expect(subject.due_date(start_date, duration)).to eq(expected)
+  end
+end
+
+RSpec.shared_examples 'add_days returns date' do |date:, count:, expected:|
+  it "add_days(#{date.to_fs(:wday_date)}, #{count}) => #{expected.to_fs(:wday_date)}" do
+    expect(subject.add_days(date, count)).to eq(expected)
+  end
+end
+
+RSpec.shared_examples 'soonest working day' do |date:, expected:|
+  it "soonest_working_day(#{date.to_fs(:wday_date)}) => #{expected.to_fs(:wday_date)}" do
+    expect(subject.soonest_working_day(date)).to eq(expected)
+  end
+end
+
+RSpec.shared_examples 'delta' do |previous:, current:, expected:|
+  it "delta(previous: #{previous.to_fs(:wday_date)}, current: #{current.to_fs(:wday_date)}) => #{expected} days" do
+    expect(subject.delta(previous:, current:)).to eq(expected)
+  end
+
+  # check inverse: delta(a, b) == -delta(b, a)
+  it "delta(previous: #{current.to_fs(:wday_date)}, current: #{previous.to_fs(:wday_date)}) => #{-expected} days" do
+    expect(subject.delta(previous: current, current: previous)).to eq(-expected)
+  end
+end

spec/services/work_packages/shared/working_days_spec.rb

@@ -0,0 +1,244 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'rails_helper'
+require_relative 'shared_examples_days'
+
+RSpec.describe WorkPackages::Shared::WorkingDays do
+  subject { described_class.new }
+
+  friday_2022_07_29 = Date.new(2022, 7, 29)
+  saturday_2022_07_30 = Date.new(2022, 7, 30)
+  sunday_2022_07_31 = Date.new(2022, 7, 31)
+  monday_2022_08_01 = Date.new(2022, 8, 1)
+  wednesday_2022_08_03 = Date.new(2022, 8, 3)
+
+  describe '#duration' do
+    it 'returns the duration for a given start date and due date' do
+      expect(subject.duration(sunday_2022_07_31, sunday_2022_07_31 + 6)).to eq(7)
+    end
+
+    context 'without any week days created' do
+      it 'considers all days as working days and returns the number of days between two dates, inclusive' do
+        expect(subject.duration(sunday_2022_07_31, sunday_2022_07_31 + 6)).to eq(7)
+        expect(subject.duration(sunday_2022_07_31, sunday_2022_07_31 + 50)).to eq(51)
+      end
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      include_examples 'it returns duration', 0, sunday_2022_07_31, sunday_2022_07_31
+      include_examples 'it returns duration', 5, sunday_2022_07_31, Date.new(2022, 8, 5)
+      include_examples 'it returns duration', 5, sunday_2022_07_31, Date.new(2022, 8, 6)
+      include_examples 'it returns duration', 5, sunday_2022_07_31, Date.new(2022, 8, 7)
+      include_examples 'it returns duration', 6, sunday_2022_07_31, Date.new(2022, 8, 8)
+      include_examples 'it returns duration', 7, sunday_2022_07_31, Date.new(2022, 8, 9)
+
+      include_examples 'it returns duration', 1, monday_2022_08_01, monday_2022_08_01
+      include_examples 'it returns duration', 5, monday_2022_08_01, Date.new(2022, 8, 5)
+      include_examples 'it returns duration', 5, monday_2022_08_01, Date.new(2022, 8, 6)
+      include_examples 'it returns duration', 5, monday_2022_08_01, Date.new(2022, 8, 7)
+      include_examples 'it returns duration', 6, monday_2022_08_01, Date.new(2022, 8, 8)
+      include_examples 'it returns duration', 7, monday_2022_08_01, Date.new(2022, 8, 9)
+
+      include_examples 'it returns duration', 3, wednesday_2022_08_03, Date.new(2022, 8, 5)
+      include_examples 'it returns duration', 3, wednesday_2022_08_03, Date.new(2022, 8, 6)
+      include_examples 'it returns duration', 3, wednesday_2022_08_03, Date.new(2022, 8, 7)
+      include_examples 'it returns duration', 4, wednesday_2022_08_03, Date.new(2022, 8, 8)
+      include_examples 'it returns duration', 5, wednesday_2022_08_03, Date.new(2022, 8, 9)
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      include_examples 'it returns duration', 0, Date.new(2022, 12, 25), Date.new(2022, 12, 25)
+      include_examples 'it returns duration', 1, Date.new(2022, 12, 24), Date.new(2022, 12, 25)
+      include_examples 'it returns duration', 8, Date.new(2022, 12, 24), Date.new(2023, 1, 2)
+    end
+
+    context 'without start date', with_flag: { work_packages_duration_field_active: true } do
+      it 'returns nil' do
+        expect(subject.duration(nil, sunday_2022_07_31)).to be_nil
+      end
+
+      context 'when work packages duration field is inactive', with_flag: { work_packages_duration_field_active: false } do
+        it 'returns 1' do
+          expect(subject.duration(nil, sunday_2022_07_31)).to eq(1)
+        end
+      end
+    end
+
+    context 'without due date', with_flag: { work_packages_duration_field_active: true } do
+      it 'returns nil' do
+        expect(subject.duration(sunday_2022_07_31, nil)).to be_nil
+      end
+
+      context 'when work packages duration field is inactive', with_flag: { work_packages_duration_field_active: false } do
+        it 'returns 1' do
+          expect(subject.duration(sunday_2022_07_31, nil)).to eq(1)
+        end
+      end
+    end
+  end
+
+  describe '#due_date' do
+    it 'returns the due date for a start date and a duration' do
+      expect(subject.due_date(monday_2022_08_01, 1)).to eq(monday_2022_08_01)
+    end
+
+    it 'raises an error if duration is 0 or negative' do
+      expect { subject.due_date(monday_2022_08_01, 0) }
+        .to raise_error ArgumentError, 'duration must be strictly positive'
+      expect { subject.due_date(monday_2022_08_01, -10) }
+        .to raise_error ArgumentError, 'duration must be strictly positive'
+    end
+
+    it 'returns nil if start_date is nil' do
+      expect(subject.due_date(nil, 1)).to be_nil
+    end
+
+    it 'returns nil if duration is nil' do
+      expect(subject.due_date(monday_2022_08_01, nil)).to be_nil
+    end
+
+    context 'without any week days created' do
+      it 'returns the due date considering all days as working days' do
+        expect(subject.due_date(monday_2022_08_01, 1)).to eq(monday_2022_08_01)
+        expect(subject.due_date(monday_2022_08_01, 7)).to eq(monday_2022_08_01 + 6) # Sunday of same week
+      end
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      include_examples 'due_date', start_date: monday_2022_08_01, duration: 1, expected: monday_2022_08_01
+      include_examples 'due_date', start_date: monday_2022_08_01, duration: 5, expected: monday_2022_08_01 + 4.days
+      include_examples 'due_date', start_date: wednesday_2022_08_03, duration: 10, expected: wednesday_2022_08_03 + 13.days
+
+      # really contrived one... Unlikely to happen.
+      include_examples 'due_date', start_date: saturday_2022_07_30, duration: 1, expected: monday_2022_08_01
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      include_examples 'due_date', start_date: Date.new(2022, 12, 24), duration: 2, expected: Date.new(2022, 12, 26)
+      include_examples 'due_date', start_date: Date.new(2022, 12, 24), duration: 8, expected: Date.new(2023, 1, 2)
+    end
+  end
+
+  describe '#add_days' do
+    it 'when positive, adds the number of working days to the date, ignoring non-working days' do
+      create(:week_day, day: 5, working: false)
+      create(:non_working_day, date: wednesday_2022_08_03)
+
+      # Wednesday is skipped (non working day)
+      expect(subject.add_days(monday_2022_08_01, 2)).to eq(Date.new(2022, 8, 4))
+
+      # Wednesday is skipped (non working day) + Friday is skipped (non working week day)
+      expect(subject.add_days(monday_2022_08_01, 7)).to eq(Date.new(2022, 8, 10))
+
+      # Wednesday is skipped (non working day) + Friday is skipped twice (non working week day)
+      expect(subject.add_days(monday_2022_08_01, 14)).to eq(Date.new(2022, 8, 18))
+    end
+
+    it 'when negative, removes the number of working days to the date, ignoring non-working days' do
+      create(:week_day, day: 5, working: false)
+      create(:non_working_day, date: sunday_2022_07_31)
+
+      # Sunday is skipped (non working day)
+      expect(subject.add_days(monday_2022_08_01, -1)).to eq(Date.new(2022, 7, 30)) # Saturday
+
+      # Sunday is skipped (non working day) + Friday is skipped (non working week day)
+      expect(subject.add_days(monday_2022_08_01, -2)).to eq(Date.new(2022, 7, 28)) # Thursday
+
+      # Sunday is skipped (non working day) + Friday is skipped twice (non working week day)
+      expect(subject.add_days(monday_2022_08_01, -8)).to eq(Date.new(2022, 7, 21)) # Wednesday
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      include_examples 'add_days returns date', date: saturday_2022_07_30, count: 0, expected: saturday_2022_07_30
+      include_examples 'add_days returns date', date: saturday_2022_07_30, count: 1, expected: monday_2022_08_01
+      include_examples 'add_days returns date', date: saturday_2022_07_30, count: -1, expected: friday_2022_07_29
+
+      include_examples 'add_days returns date', date: sunday_2022_07_31, count: 0, expected: sunday_2022_07_31
+      include_examples 'add_days returns date', date: sunday_2022_07_31, count: 1, expected: monday_2022_08_01
+      include_examples 'add_days returns date', date: sunday_2022_07_31, count: -1, expected: friday_2022_07_29
+
+      include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: 100, expected: Date.new(2022, 11, 2)
+      include_examples 'add_days returns date', date: Date.new(2022, 6, 15), count: -100, expected: Date.new(2022, 1, 26)
+
+      include_examples 'add_days returns date', date: Date.new(2022, 1, 1), count: 365, expected: Date.new(2023, 5, 26)
+      include_examples 'add_days returns date', date: Date.new(2022, 12, 31), count: -365, expected: Date.new(2021, 8, 9)
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      include_examples 'add_days returns date', date: Date.new(2022, 12, 24), count: 1, expected: Date.new(2022, 12, 26)
+      include_examples 'add_days returns date', date: Date.new(2022, 12, 24), count: 7, expected: Date.new(2023, 1, 2)
+
+      include_examples 'add_days returns date', date: Date.new(2022, 12, 26), count: -1, expected: Date.new(2022, 12, 24)
+      include_examples 'add_days returns date', date: Date.new(2023, 1, 2), count: -7, expected: Date.new(2022, 12, 24)
+    end
+  end
+
+  describe '#soonest_working_day' do
+    it 'returns the soonest working day from the given day' do
+      expect(subject.soonest_working_day(sunday_2022_07_31)).to eq(sunday_2022_07_31)
+    end
+
+    it 'returns nil if given date is nil' do
+      expect(subject.soonest_working_day(nil)).to be_nil
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      include_examples 'soonest working day', date: friday_2022_07_29, expected: friday_2022_07_29
+      include_examples 'soonest working day', date: saturday_2022_07_30, expected: monday_2022_08_01
+      include_examples 'soonest working day', date: sunday_2022_07_31, expected: monday_2022_08_01
+      include_examples 'soonest working day', date: monday_2022_08_01, expected: monday_2022_08_01
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      include_examples 'soonest working day', date: Date.new(2022, 12, 25), expected: Date.new(2022, 12, 26)
+      include_examples 'soonest working day', date: Date.new(2022, 12, 31), expected: Date.new(2022, 12, 31)
+      include_examples 'soonest working day', date: Date.new(2023, 1, 1), expected: Date.new(2023, 1, 2)
+    end
+  end
+
+  describe '#delta' do
+    it 'returns the number of shift from one working day to another between two dates' do
+      expect(subject.delta(previous: monday_2022_08_01, current: wednesday_2022_08_03)).to eq(2)
+      expect(subject.delta(previous: wednesday_2022_08_03, current: monday_2022_08_01)).to eq(-2)
+    end
+
+    context 'with weekend days (Saturday and Sunday)', :weekend_saturday_sunday do
+      include_examples 'delta', previous: friday_2022_07_29, current: saturday_2022_07_30, expected: 0
+      include_examples 'delta', previous: saturday_2022_07_30, current: monday_2022_08_01, expected: 0
+      include_examples 'delta', previous: sunday_2022_07_31, current: monday_2022_08_01, expected: 0
+      include_examples 'delta', previous: friday_2022_07_29, current: monday_2022_08_01, expected: 1
+      include_examples 'delta', previous: friday_2022_07_29, current: Date.new(2022, 8, 5), expected: 5
+      include_examples 'delta', previous: friday_2022_07_29, current: Date.new(2022, 8, 8), expected: 6
+    end
+
+    context 'with non working days (Christmas 2022-12-25 and new year\'s day 2023-01-01)', :christmas_2022_new_year_2023 do
+      include_examples 'delta', previous: Date.new(2022, 12, 27), current: Date.new(2022, 12, 20), expected: -6
+    end
+  end
+end

spec/services/work_packages/update_service_integration_spec.rb

@@ -901,7 +901,8 @@ describe WorkPackages::UpdateService, 'integration tests', type: :model, with_ma
     # rubocop:enable RSpec/ExampleLength
   end
 
-  describe 'rescheduling work packages with a parent having a follows relation (Regression #43220)' do
+  describe 'rescheduling work packages with a parent having a follows relation (Regression #43220)',
+           with_flag: { work_packages_duration_field_active: true } do
     let(:predecessor_work_package_attributes) do
       work_package_attributes.merge(
         start_date: Time.zone.today + 1.day,

spec/support/schedule_helpers.rb

@@ -0,0 +1,48 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+Dir[Rails.root.join('spec/support/schedule_helpers/*.rb')].each { |f| require f }
+
+RSpec.configure do |config|
+  config.extend ScheduleHelpers::LetSchedule
+  config.include ScheduleHelpers::ExampleMethods
+
+  RSpec::Matchers.define :match_schedule do |expected|
+    match do |actual_work_packages|
+      expected_chart = ScheduleHelpers::Chart.for(expected)
+      actual_chart = ScheduleHelpers::Chart.from_work_packages(actual_work_packages)
+
+      @expected, @actual = ScheduleHelpers::ChartRepresenter.normalized_to_s(expected_chart, actual_chart)
+
+      values_match? @expected, @actual
+    end
+
+    diffable
+    attr_reader :expected, :actual
+  end
+end

spec/support/schedule_helpers/chart.rb

@@ -0,0 +1,246 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module ScheduleHelpers
+  # Contains work packages and relations information from a chart
+  # representation.
+  #
+  # The work package information are:
+  # * subject
+  # * start_date
+  # * due_date
+  #
+  # The relations information are limited to follows relations and are retrieved
+  # with +#predecessors_by_follower+
+  #
+  # The chart uses different symbols in the timeline to represent a work package
+  # start and due dates:
+  # * +X+: a day of the work package duration. The first +X+ is the start date,
+  #   the last +X+ is the due date.
+  # * +[+: the work package start date. Can be used instead of +X+ when the work
+  #   package has no due date.
+  # * +]+: the work package due date. Can be used instead of +X+ when the work
+  #   package has no start date.
+  # * +_+: ignored but useful as a placeholder to highlight particular days, for
+  #   instance to highlight the previous dates of a work package.
+  class Chart
+    FIRST_CELL_TEXT = 'days'.freeze
+    WEEK_DAYS_TEXT = 'MTWTFSS'.freeze
+
+    attr_reader :id_column_size, :first_day, :last_day, :monday
+
+    def self.for(representation)
+      builder = ChartBuilder.new
+      builder.parse(representation)
+    end
+
+    def self.from_work_packages(work_packages)
+      ChartBuilder.new.use_work_packages(Array(work_packages))
+    end
+
+    def initialize
+      self.monday = next_monday
+      self.id_column_size = FIRST_CELL_TEXT.length
+    end
+
+    # duplicates the chart with different representation properties
+    def with(order: work_package_names, id_column_size: self.id_column_size, first_day: self.first_day, last_day: self.last_day)
+      chart = Chart.new
+      extra_names = work_package_names - order
+      chart.work_packages_attributes = work_packages_attributes.index_by { _1[:name] }.values_at(*(order + extra_names)).compact
+      chart.monday = monday
+      chart.id_column_size = id_column_size
+      chart.first_day = first_day
+      chart.last_day = last_day
+      chart.predecessors_by_followers = predecessors_by_followers
+      chart.delays_between = delays_between
+      chart.parent_by_child = parent_by_child
+      chart
+    end
+
+    # Sets the origin of the calendar, represented by +M+ on the first line (M as
+    # in Monday).
+    def monday=(monday)
+      raise ArgumentError, "#{monday} is not a Monday" unless monday.wday == 1
+
+      extend_calendar_range(monday, monday + 6.days)
+      @monday = monday
+    end
+
+    def validate
+      work_package_names.each do |follower|
+        predecessors_by_follower(follower).each do |predecessor|
+          unless work_package_attributes(predecessor)
+            raise "unable to find predecessor #{predecessor.inspect} " \
+                  "in property \"follows #{predecessor}\" " \
+                  "for work package #{follower.inspect}"
+          end
+        end
+      end
+    end
+
+    def work_packages_attributes
+      @work_packages_attributes ||= []
+    end
+
+    def work_package_attributes(name)
+      work_packages_attributes.find { |wpa| wpa[:name] == name.to_sym }
+    end
+
+    def work_package_names
+      work_packages_attributes.pluck(:name)
+    end
+
+    def predecessors_by_follower(follower)
+      predecessors_by_followers[follower]
+    end
+
+    def delay_between(predecessor:, follower:)
+      delays_between.fetch([predecessor, follower])
+    end
+
+    def add_work_package(attributes)
+      extend_calendar_range(*attributes.values_at(:start_date, :due_date))
+      extend_id_column_size(*attributes.values_at(:subject))
+      work_packages_attributes << attributes.merge(name: attributes[:subject].to_sym)
+    end
+
+    def set_duration(name, duration)
+      unless duration.is_a?(Integer) && duration > 0
+        raise ArgumentError, "unable to set duration for #{name}: " \
+                             "duration must be a positive integer (got #{duration.inspect})"
+      end
+      attributes = work_package_attributes(name.to_sym)
+      dates_attributes = attributes.slice(:start_date, :due_date).compact
+      if dates_attributes.any?(&:present?)
+        raise ArgumentError, "unable to set duration for #{name}: " \
+                             "#{dates_attributes.keys.join(' and ')} is set"
+      end
+      attributes[:duration] = duration
+    end
+
+    def add_follows_relation(predecessor:, follower:, delay:)
+      predecessors_by_follower(follower) << predecessor
+      delays_between[[predecessor, follower]] = delay
+    end
+
+    def add_parent_relation(parent:, child:)
+      parent_by_child[child] = parent
+    end
+
+    def parent(name)
+      parent_by_child[name]
+    end
+
+    def to_s
+      representer = ChartRepresenter.new(id_column_size:, days_column_size:)
+      representer.add_row
+      representer.add_cell(FIRST_CELL_TEXT)
+      representer.add_cell(spaced_at(monday, WEEK_DAYS_TEXT))
+      work_package_names.each do |name|
+        representer.add_row
+        representer.add_cell(name.to_s)
+        representer.add_cell(span(work_package_attributes(name)))
+      end
+      representer.to_s
+    end
+
+    protected
+
+    attr_writer :work_packages_attributes,
+                :id_column_size,
+                :first_day,
+                :last_day,
+                :predecessors_by_followers,
+                :delays_between,
+                :parent_by_child
+
+    private
+
+    def extend_calendar_range(*dates)
+      self.first_day = [@first_day, *dates].compact.min
+      self.last_day = [@last_day, *dates].compact.max
+    end
+
+    def extend_id_column_size(name)
+      self.id_column_size = [id_column_size, name.length].max
+    end
+
+    def days_column_size
+      (first_day..last_day).count
+    end
+
+    def spaced_at(date, text)
+      nb_days = date - first_day
+      (" " * nb_days) + text
+    end
+
+    def span(attributes)
+      case attributes
+      in { start_date: nil, due_date: nil }
+        ''
+      in { start_date:, due_date: nil }
+        spaced_at(start_date, '[')
+      in { start_date: nil, due_date: }
+        spaced_at(due_date, ']')
+      in { start_date:, due_date: }
+        days = days_for(attributes)
+        span = (start_date..due_date).map do |date|
+          days.working?(date) ? 'X' : '.'
+        end.join
+        spaced_at(start_date, span)
+      end
+    end
+
+    def days_for(attributes)
+      if attributes[:ignore_non_working_days]
+        WorkPackages::Shared::AllDays.new
+      else
+        WorkPackages::Shared::WorkingDays.new
+      end
+    end
+
+    def next_monday
+      date = Time.zone.today
+      date += 1.day while date.wday != 1
+      date
+    end
+
+    def predecessors_by_followers
+      @predecessors_by_followers ||= Hash.new { |h, k| h[k] = [] }
+    end
+
+    def delays_between
+      @delays_between ||= Hash.new(0)
+    end
+
+    def parent_by_child
+      @parent_by_child ||= {}
+    end
+  end
+end

spec/support/schedule_helpers/chart_builder.rb

@@ -0,0 +1,131 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module ScheduleHelpers
+  # Builds a +Chart+ instance from a visual chart representation.
+  #
+  # Example:
+  #
+  #   ChartBuilder.new.parse(<<~CHART)
+  #     days       | MTWTFSS   |
+  #     main       | XX        |
+  #     follower   |   XXX     | follows main
+  #     start_only |  [        |
+  #     due_only   |    ]      |
+  #     no_dates   |           |
+  #   CHART
+  class ChartBuilder
+    attr_reader :chart
+
+    def initialize
+      @chart = Chart.new
+    end
+
+    def parse(representation)
+      lines = representation.split("\n")
+      header = lines.shift
+      parse_header(header)
+      lines.each do |line|
+        parse_line(line)
+      end
+      chart.validate
+      chart
+    end
+
+    def use_work_packages(work_packages)
+      work_packages.each do |work_package|
+        chart.add_work_package(work_package.slice(:subject, :start_date, :due_date, :ignore_non_working_days))
+      end
+      chart
+    end
+
+    private
+
+    def parse_header(header)
+      _, week_days = header.split(' | ', 2)
+      unless week_days.include?(Chart::WEEK_DAYS_TEXT)
+        raise ArgumentError,
+              "First header line of schedule chart must contain #{Chart::WEEK_DAYS_TEXT} to indicate day names and have an origin"
+      end
+
+      @nb_days_from_origin_monday = week_days.index(Chart::WEEK_DAYS_TEXT.first)
+    end
+
+    def parse_line(line)
+      case line
+      when ''
+        # noop
+      when / \| /
+        parse_work_package_line(line)
+      else
+        raise "unable to parse line #{line.inspect}"
+      end
+    end
+
+    def parse_work_package_line(line)
+      name, timespan, properties = line.split(' | ', 3)
+      name.strip!
+      attributes = { subject: name }
+      attributes.update(parse_timespan(timespan))
+      chart.add_work_package(attributes)
+
+      properties.to_s.split(',').map(&:strip).each do |property|
+        parse_properties(name, property)
+      end
+    end
+
+    def parse_properties(name, property)
+      case property
+      when /^follows (\w+)(?: with delay (\d+))?/
+        chart.add_follows_relation(
+          predecessor: $1.to_sym,
+          follower: name.to_sym,
+          delay: $2.to_i
+        )
+      when /^child of (\w+)/
+        chart.add_parent_relation(
+          parent: $1.to_sym,
+          child: name.to_sym
+        )
+      when /^duration (\d+)/
+        chart.set_duration(name, $1.to_i)
+      else
+        raise "unable to parse property #{property.inspect} for line #{name.inspect}"
+      end
+    end
+
+    def parse_timespan(timespan)
+      start_pos = timespan.index('[') || timespan.index('X')
+      due_pos = timespan.rindex(']') || timespan.rindex('X')
+      {
+        start_date: start_pos && (chart.monday - @nb_days_from_origin_monday + start_pos),
+        due_date: due_pos && (chart.monday - @nb_days_from_origin_monday + due_pos)
+      }
+    end
+  end
+end

spec/support/schedule_helpers/chart_representer.rb

@@ -0,0 +1,67 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module ScheduleHelpers
+  class ChartRepresenter
+    LINE = "%<id>s | %<days>s |".freeze
+
+    def self.normalized_to_s(reference_chart, other_chart)
+      order = reference_chart.work_package_names
+      id_column_size = [reference_chart, other_chart].map(&:id_column_size).max
+      first_day = [reference_chart, other_chart].map(&:first_day).min
+      last_day = [reference_chart, other_chart].map(&:last_day).max
+      [reference_chart, other_chart]
+        .map { |chart| chart.with(order:, id_column_size:, first_day:, last_day:) }
+        .map(&:to_s)
+    end
+
+    def initialize(id_column_size:, days_column_size:)
+      @id_column_size = id_column_size
+      @days_column_size = days_column_size
+    end
+
+    def add_row
+      rows << []
+    end
+
+    def add_cell(text)
+      rows.last << text
+    end
+
+    def rows
+      @rows ||= []
+    end
+
+    def to_s
+      line_template = "%<id>-#{@id_column_size}s | %<days>-#{@days_column_size}s |"
+      rows.map do |row|
+        line_template % { id: row[0], days: row[1] }
+      end.join("\n")
+    end
+  end
+end

spec/support/schedule_helpers/example_methods.rb

@@ -0,0 +1,98 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module ScheduleHelpers
+  module ExampleMethods
+    # Change the given work packages according to the given chart representation.
+    # Work packages are changed without being saved.
+    #
+    # For instance:
+    #
+    #   before do
+    #     change_schedule([main], <<~CHART)
+    #       days | MTWTFSS |
+    #       main | XX      |
+    #     CHART
+    #   end
+    #
+    # is equivalent to:
+    #
+    #   before do
+    #     main.start_date = monday
+    #     main.due_date = tuesday
+    #   end
+    def change_schedule(work_packages, chart)
+      Chart.for(chart).work_packages_attributes.each do |attributes|
+        work_package = work_packages.find { |wp| wp.subject == attributes[:subject] }
+        unless work_package
+          raise ArgumentError, "no work package with subject #{attributes[:subject]} given; " \
+                               "available work packages are #{work_packages.pluck(:subject).to_sentence}"
+        end
+
+        attributes.slice(:start_date, :due_date).each do |attribute, value|
+          work_package.send(:"#{attribute}=", value)
+        end
+      end
+    end
+
+    # Expect the given work packages to match a visual chart representation.
+    #
+    # For instance:
+    #
+    #   it 'is scheduled' do
+    #     expect_schedule(work_packages, <<~CHART)
+    #       days     | MTWTFSS   |
+    #       main     | XX        |
+    #       follower |   XXX     |
+    #     CHART
+    #   end
+    #
+    # is equivalent to:
+    #
+    #   it 'is scheduled' do
+    #     main = work_packages.find { _1.id == main.id } || main
+    #     expect(main.start_date).to eq(next_monday)
+    #     expect(main.due_date).to eq(next_monday + 1.day)
+    #     follower = work_packages.find { _1.id == follower.id } || follower
+    #     expect(follower.start_date).to eq(next_monday + 2.days)
+    #     expect(follower.due_date).to eq(next_monday + 4.days)
+    #   end
+    def expect_schedule(work_packages, chart)
+      by_id = work_packages.index_by(&:id)
+      chart = Chart.for(chart)
+      chart.work_packages_attributes.each do |attributes|
+        name = attributes[:name]
+        raise ArgumentError, "unable to find WorkPackage :#{name}" unless respond_to?(name)
+
+        work_package = send(name)
+        work_package = by_id[work_package.id] if by_id.has_key?(work_package.id)
+        expect(work_package).to have_attributes(attributes.slice(:subject, :start_date, :due_date))
+      end
+    end
+  end
+end

spec/support/schedule_helpers/let_schedule.rb

@@ -0,0 +1,107 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module ScheduleHelpers
+  module LetSchedule
+    # Declare work packages and relations from a visual chart representation.
+    #
+    # For instance:
+    #
+    #   let_schedule(<<~CHART)
+    #     days       | MTWTFSS   |
+    #     main       | XX        |
+    #     follower   |   XXX     | follows main
+    #     start_only |  [        |
+    #     due_only   |    ]      |
+    #   CHART
+    #
+    # is equivalent to:
+    #
+    #   let!(:schedule_chart) do
+    #     chart = <...parse_chart(CHART)...>
+    #     main
+    #     follower
+    #     start_only
+    #     due_only
+    #     relation_follower_follows_main
+    #     chart
+    #   end
+    #   let(:main) do
+    #     create(:work_package, subject: 'main', start_date: next_monday, due_date: next_monday + 1.day)
+    #   end
+    #   let(:follower) do
+    #     create(:work_package, subject: 'follower', start_date: next_monday + 2.days, due_date: next_monday + 4.days) }
+    #   end
+    #   let(:relation_follower_follows_main) do
+    #     create(:follows_relation, from: follower, to: main, delay: 0) }
+    #   end
+    #   let(:start_only) do
+    #     create(:work_package, subject: 'start_only', start_date: next_monday + 1.day) }
+    #   end
+    #   let(:due_only) do
+    #     create(:work_package, subject: 'due_only', due_date: next_monday + 3.days) }
+    #   end
+    def let_schedule(chart_representation, **extra_attributes)
+      # To be able to use `travel_to` in a before hook, the dates in the chart
+      # must be lazy evaluated in a let statement.
+      let(:schedule_chart) { Chart.for(chart_representation) }
+      let!(:__evaluate_work_packages_from_schedule_chart) do
+        schedule_chart.work_package_names.each do |name|
+          # force evaluation of work package
+          send(name)
+          schedule_chart.predecessors_by_follower(name).each do |predecessor|
+            # force evaluation of relation
+            send("relation_#{name}_follows_#{predecessor}")
+          end
+        end
+      end
+
+      # we still need to parse the chart to get the work package names and relations
+      chart = Chart.for(chart_representation)
+      chart.work_package_names.each do |name|
+        let(name) do
+          attributes = schedule_chart
+            .work_package_attributes(name)
+            .excluding(:name)
+            .reverse_merge(extra_attributes)
+            .merge(parent: schedule_chart.parent(name) ? send(schedule_chart.parent(name)) : nil)
+          create(:work_package, attributes)
+        end
+        chart.predecessors_by_follower(name).each do |predecessor|
+          relation_alias = "relation_#{name}_follows_#{predecessor}"
+          let(relation_alias) do
+            create(:follows_relation,
+                   from: send(name),
+                   to: send(predecessor),
+                   delay: schedule_chart.delay_between(predecessor:, follower: name))
+          end
+        end
+      end
+    end
+  end
+end

spec/support_spec/schedule_helpers/chart_builder_spec.rb

@@ -0,0 +1,171 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'spec_helper'
+
+describe ScheduleHelpers::ChartBuilder do
+  include ActiveSupport::Testing::TimeHelpers
+
+  let(:fake_today) { Date.new(2022, 6, 16) } # Thursday 16 June 2022
+  let(:monday) { Date.new(2022, 6, 20) } # Monday 20 June
+  let(:tuesday) { Date.new(2022, 6, 21) }
+  let(:wednesday) { Date.new(2022, 6, 22) }
+  let(:thursday) { Date.new(2022, 6, 23) }
+  let(:friday) { Date.new(2022, 6, 24) }
+  let(:saturday) { Date.new(2022, 6, 25) }
+  let(:sunday) { Date.new(2022, 6, 26) }
+
+  subject(:builder) { described_class.new }
+
+  describe 'happy path' do
+    let(:next_tuesday) { tuesday + 7.days }
+
+    before do
+      travel_to(fake_today)
+    end
+
+    it 'reads a chart and convert it into objects with attributes' do
+      chart = builder.parse(<<~CHART)
+        days       | MTWTFSS   |
+        main       | XX        |
+        other      |    XX..XX |
+        follower   |   XXX     | follows main
+        start_only |  [        |
+        due_only   |     ]     |
+        no_dates   |           |
+      CHART
+      expect(chart.work_packages_attributes).to eq(
+        [
+          { name: :main, subject: 'main', start_date: monday, due_date: tuesday },
+          { name: :other, subject: 'other', start_date: thursday, due_date: next_tuesday },
+          { name: :follower, subject: 'follower', start_date: wednesday, due_date: friday },
+          { name: :start_only, subject: 'start_only', start_date: tuesday, due_date: nil },
+          { name: :due_only, subject: 'due_only', start_date: nil, due_date: friday },
+          { name: :no_dates, subject: 'no_dates', start_date: nil, due_date: nil }
+        ]
+      )
+      expect(chart.predecessors_by_follower(:main)).to eq([])
+      expect(chart.predecessors_by_follower(:other)).to eq([])
+      expect(chart.predecessors_by_follower(:follower)).to eq([:main])
+    end
+  end
+
+  describe 'origin day' do
+    before do
+      travel_to(fake_today)
+    end
+
+    it 'is identified by the M in MTWTFSS and corresponds to next monday' do
+      chart = builder.parse(<<~CHART)
+        days       | MTWTFSS |
+      CHART
+      expect(chart.monday).to eq(monday)
+      expect(chart.monday).to eq(chart.first_day)
+    end
+
+    it 'is not identified by mtwtfss which can be used as documentation instead' do
+      chart = builder.parse(<<~CHART)
+        days | mtwtfssMTWTFSSmtwtfss |
+        wp   |   X                   |
+      CHART
+      expect(chart.monday).to eq(monday)
+      expect(chart.first_day).to eq(chart.work_package_attributes(:wp)[:start_date])
+    end
+  end
+
+  describe 'properties' do
+    describe 'follows <name>' do
+      it 'adds a follows relation to the named' do
+        chart = builder.parse(<<~CHART)
+          days       | MTWTFSS   |
+          main       |           |
+          follower   |           | follows main
+        CHART
+        expect(chart.predecessors_by_follower(:follower)).to eq([:main])
+        expect(chart.delay_between(predecessor: :main, follower: :follower)).to eq(0)
+      end
+
+      it 'can be declared in any order' do
+        chart = builder.parse(<<~CHART)
+          days       | MTWTFSS   |
+          follower   |           | follows main
+          main       |           |
+        CHART
+        expect(chart.predecessors_by_follower(:follower)).to eq([:main])
+        expect(chart.delay_between(predecessor: :main, follower: :follower)).to eq(0)
+      end
+    end
+
+    describe 'follows <name> with delay <n>' do
+      it 'adds a follows relation to the named with a delay' do
+        chart = builder.parse(<<~CHART)
+          days       | MTWTFSS   |
+          main       |           |
+          follower   |           | follows main with delay 3
+        CHART
+        expect(chart.predecessors_by_follower(:follower)).to eq([:main])
+        expect(chart.delay_between(predecessor: :main, follower: :follower)).to eq(3)
+      end
+    end
+
+    describe 'child of <name>' do
+      it 'sets the parent to the named one' do
+        chart = builder.parse(<<~CHART)
+          days        | MTWTFSS |
+          parent      |         | child of grandparent
+          main        |         | child of parent
+          grandparent |         |
+        CHART
+        expect(chart.parent(:grandparent)).to be_nil
+        expect(chart.parent(:parent)).to eq(:grandparent)
+        expect(chart.parent(:main)).to eq(:parent)
+      end
+    end
+
+    describe 'duration <int>' do
+      it 'sets the duration of the work package' do
+        chart = builder.parse(<<~CHART)
+          days        | MTWTFSS |
+          main        |         | duration 3
+        CHART
+        expect(chart.work_package_attributes(:main)).to include(duration: 3)
+      end
+    end
+  end
+
+  describe 'error handling' do
+    it 'raises an error if the relation references a non-existing work package predecessor' do
+      expect do
+        builder.parse(<<~CHART)
+                    | MTWTFSS |
+          follower  |   XX    | follows main
+        CHART
+      end.to raise_error(RuntimeError, /unable to find predecessor :main in property "follows main" for work package :follower/)
+    end
+  end
+end

spec/support_spec/schedule_helpers/chart_representer_spec.rb

@@ -0,0 +1,192 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'spec_helper'
+
+describe ScheduleHelpers::ChartRepresenter do
+  let(:fake_today) { Date.new(2022, 6, 16) } # Thursday 16 June 2022
+  let(:monday) { Date.new(2022, 6, 20) } # Monday 20 June
+  let(:tuesday) { Date.new(2022, 6, 21) }
+  let(:wednesday) { Date.new(2022, 6, 22) }
+  let(:thursday) { Date.new(2022, 6, 23) }
+  let(:friday) { Date.new(2022, 6, 24) }
+  let(:saturday) { Date.new(2022, 6, 25) }
+  let(:sunday) { Date.new(2022, 6, 26) }
+
+  describe '#normalized_to_s' do
+    let!(:week_days) { create(:week_days) }
+
+    context 'when both charts have different work packages items and/or order' do
+      def to_first_columns(charts)
+        charts.map { _1.split("\n").map(&:split).map(&:first).join(' ') }
+      end
+
+      it 'returns charts ascii with work packages in same order as the first given chart' do
+        initial_expected_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       |    MTWTFSS  |
+            main       | X..X        |
+            other      |      XXX..X |
+          CHART
+        initial_actual_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       |    MTWTFSS  |
+            other      |      XXX..X |
+            main       | X..X        |
+          CHART
+
+        expected_column, actual_column =
+          described_class
+            .normalized_to_s(initial_expected_chart, initial_actual_chart)
+            .then(&method(:to_first_columns))
+
+        expect(actual_column).to eq(expected_column)
+      end
+
+      it 'pushes extra elements of the second chart at the end' do
+        initial_expected_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       |    MTWTFSS  |
+            main       | X..X        |
+            other      |      XXX..X |
+          CHART
+        initial_actual_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       |    MTWTFSS  |
+            extra      |             |
+            main       | X..X        |
+            other      |      XXX..X |
+          CHART
+
+        expected_column, actual_column =
+          described_class
+            .normalized_to_s(initial_expected_chart, initial_actual_chart)
+            .then(&method(:to_first_columns))
+
+        expect(expected_column).to eq('days main other')
+        expect(actual_column).to eq('days main other extra')
+      end
+
+      it 'keeps extra elements of the first chart at the same place' do
+        initial_expected_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       |    MTWTFSS  |
+            main       | X..X        |
+            extra      |             |
+            other      |      XXX..X |
+          CHART
+        initial_actual_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       |    MTWTFSS  |
+            main       | X..X        |
+            other      |      XXX..X |
+          CHART
+
+        expected_column, actual_column =
+          described_class
+            .normalized_to_s(initial_expected_chart, initial_actual_chart)
+            .then(&method(:to_first_columns))
+
+        expect(expected_column).to eq('days main extra other')
+        expect(actual_column).to eq('days main other')
+      end
+    end
+
+    context 'when both charts have different first column width' do
+      def to_first_cells(charts)
+        charts.map { _1.split("\n").first.split(" | ").first }
+      end
+
+      it 'returns charts ascii with identical first column width' do
+        tiny_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days      | MTWTFSS |
+            tiny name |   XX    |
+          CHART
+        longer_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days             | MTWTFSS |
+            much longer name |   XX    |
+          CHART
+
+        # tiny_chart as reference chart
+        first_cell, second_cell =
+          described_class
+            .normalized_to_s(tiny_chart, longer_chart)
+            .then(&method(:to_first_cells))
+
+        expect(first_cell).to eq('days            ')
+        expect(first_cell).to eq(second_cell)
+
+        # tiny_chart as reference chart
+        first_cell, second_cell =
+          described_class
+            .normalized_to_s(longer_chart, tiny_chart)
+            .then(&method(:to_first_cells))
+
+        expect(first_cell).to eq('days            ')
+        expect(first_cell).to eq(second_cell)
+      end
+    end
+
+    context 'when both charts cover different time periods' do
+      def to_headers(charts)
+        charts.map { _1.split("\n").first }
+      end
+
+      it 'returns charts ascii with identical time periods' do
+        larger_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       |   MTWTFSS   |
+            main       | XXXXXXXXXXX |
+          CHART
+        shorter_chart =
+          ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+            days       | MTWTFSS |
+            main       |   XXX   |
+          CHART
+
+        # larger_chart as reference
+        first_header, second_header =
+          described_class
+            .normalized_to_s(larger_chart, shorter_chart)
+            .then(&method(:to_headers))
+
+        expect(first_header).to eq(second_header)
+
+        # shorter_chart as reference
+        first_header, second_header =
+          described_class
+            .normalized_to_s(shorter_chart, larger_chart)
+            .then(&method(:to_headers))
+
+        expect(first_header).to eq(second_header)
+      end
+    end
+  end
+end

spec/support_spec/schedule_helpers/chart_spec.rb

@@ -0,0 +1,227 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'spec_helper'
+
+describe ScheduleHelpers::Chart do
+  include ActiveSupport::Testing::TimeHelpers
+
+  let(:fake_today) { Date.new(2022, 6, 16) } # Thursday 16 June 2022
+  let(:monday) { Date.new(2022, 6, 20) } # Monday 20 June
+  let(:tuesday) { Date.new(2022, 6, 21) }
+  let(:wednesday) { Date.new(2022, 6, 22) }
+  let(:thursday) { Date.new(2022, 6, 23) }
+  let(:friday) { Date.new(2022, 6, 24) }
+  let(:saturday) { Date.new(2022, 6, 25) }
+  let(:sunday) { Date.new(2022, 6, 26) }
+
+  subject(:chart) { described_class.new }
+
+  before do
+    travel_to(fake_today)
+  end
+
+  describe '#first_day' do
+    context 'without work packages' do
+      it 'returns the first day represented on the graph, which is next Monday' do
+        expect(chart.first_day).to eq(monday)
+      end
+    end
+
+    context 'with work packages' do
+      it 'returns the minimum between work packages dates and origin Monday' do
+        expect(chart.first_day).to eq(monday)
+
+        chart.add_work_package(subject: 'wp1', start_date: tuesday)
+        expect(chart.first_day).to eq(monday)
+
+        chart.add_work_package(subject: 'wp2', start_date: monday - 3.days)
+        expect(chart.first_day).to eq(monday - 3.days)
+
+        chart.add_work_package(subject: 'wp3', start_date: sunday)
+        expect(chart.first_day).to eq(monday - 3.days)
+
+        chart.add_work_package(subject: 'wp4', due_date: monday - 6.days)
+        expect(chart.first_day).to eq(monday - 6.days)
+      end
+    end
+
+    it 'can be set to an earlier date by setting the origin monday to an earlier date' do
+      expect(chart.first_day).to eq(monday)
+
+      # no change when origin is moved forward
+      expect { chart.monday = monday + 14.days }
+        .not_to change(chart, :first_day)
+
+      # change when origin is moved backward
+      expect { chart.monday = monday - 14.days }
+        .to change(chart, :first_day).to(monday - 14.days)
+    end
+  end
+
+  describe '#last_day' do
+    context 'without work packages' do
+      it 'returns the last day represented on the graph, which is the Sunday following origin Monday' do
+        expect(chart.last_day).to eq(sunday)
+      end
+    end
+
+    context 'with work packages' do
+      it 'returns the maximum between work packages dates and the Sunday following origin Monday' do
+        expect(chart.last_day).to eq(sunday)
+
+        chart.add_work_package(subject: 'wp1', due_date: tuesday + 7.days)
+        expect(chart.last_day).to eq(tuesday + 7.days)
+
+        chart.add_work_package(subject: 'wp2', start_date: monday - 3.days)
+        expect(chart.last_day).to eq(tuesday + 7.days)
+
+        chart.add_work_package(subject: 'wp3', start_date: monday + 20.days)
+        expect(chart.last_day).to eq(monday + 20.days)
+      end
+    end
+
+    it 'can be set to an later date by setting the origin Monday to a later date' do
+      expect(chart.last_day).to eq(sunday)
+
+      # no change when origin is moved backward
+      expect { chart.monday = monday - 14.days }
+        .not_to change(chart, :last_day)
+
+      # change when origin is moved forward
+      expect { chart.monday = monday + 14.days }
+        .to change(chart, :last_day).to(sunday + 14.days)
+    end
+  end
+
+  describe '#set_duration' do
+    it 'sets the duration for a work package' do
+      chart.add_work_package(subject: 'wp')
+      chart.set_duration('wp', 3)
+      expect(chart.work_package_attributes('wp')).to include(duration: 3)
+    end
+
+    it 'must set the duration to a positive integer' do
+      chart.add_work_package(subject: 'wp')
+      expect { chart.set_duration('wp', 0) }
+        .to raise_error(ArgumentError, 'unable to set duration for wp: duration must be a positive integer (got 0)')
+
+      expect { chart.set_duration('wp', -5) }
+        .to raise_error(ArgumentError, 'unable to set duration for wp: duration must be a positive integer (got -5)')
+
+      expect { chart.set_duration('wp', 'hello') }
+        .to raise_error(ArgumentError, 'unable to set duration for wp: duration must be a positive integer (got "hello")')
+
+      expect { chart.set_duration('wp', '42') }
+        .to raise_error(ArgumentError, 'unable to set duration for wp: duration must be a positive integer (got "42")')
+    end
+
+    it 'cannot set the duration if the work package has dates' do
+      chart.add_work_package(subject: 'wp_start', start_date: monday)
+      expect { chart.set_duration('wp_start', 3) }
+        .to raise_error(ArgumentError, 'unable to set duration for wp_start: start_date is set')
+
+      chart.add_work_package(subject: 'wp_due', due_date: monday)
+      expect { chart.set_duration('wp_due', 3) }
+        .to raise_error(ArgumentError, 'unable to set duration for wp_due: due_date is set')
+
+      chart.add_work_package(subject: 'wp_both', start_date: monday, due_date: monday)
+      expect { chart.set_duration('wp_both', 3) }
+        .to raise_error(ArgumentError, 'unable to set duration for wp_both: start_date and due_date is set')
+    end
+  end
+
+  describe '#to_s', with_flag: { work_packages_duration_field_active: true } do
+    let!(:week_days) { create(:week_days) }
+
+    context 'with a chart built from ascii representation' do
+      let(:chart) do
+        ScheduleHelpers::ChartBuilder.new.parse(<<~CHART)
+          days       |    MTWTFSS  |
+          main       | X..X        |
+          other      |      XXX..X |
+          follower   |     XXX     | follows main
+          start_only |    [        |
+          due_only   |       ]     |
+          no_dates   |             |
+        CHART
+      end
+
+      it 'returns the same ascii representation without properties information' do
+        expect(chart.to_s).to eq(<<~CHART.chomp)
+          days       |    MTWTFSS  |
+          main       | X..X        |
+          other      |      XXX..X |
+          follower   |     XXX     |
+          start_only |    [        |
+          due_only   |       ]     |
+          no_dates   |             |
+        CHART
+      end
+    end
+
+    context 'with a chart built from real work packages' do
+      let(:work_package1) { build_stubbed(:work_package, subject: 'main', start_date: monday, due_date: tuesday) }
+      let(:work_package2) do
+        build_stubbed(:work_package, subject: 'working_days', ignore_non_working_days: false,
+                                     start_date: tuesday, due_date: monday + 7.days)
+      end
+      let(:work_package2bis) do
+        build_stubbed(:work_package, subject: 'all_days', ignore_non_working_days: true,
+                                     start_date: tuesday, due_date: monday + 7.days)
+      end
+      let(:work_package3) { build_stubbed(:work_package, subject: 'start_only', start_date: monday - 3.days) }
+      let(:work_package4) { build_stubbed(:work_package, subject: 'due_only', due_date: wednesday) }
+      let(:work_package5) { build_stubbed(:work_package, subject: 'no_dates') }
+      let(:chart) do
+        ScheduleHelpers::ChartBuilder.new.use_work_packages(
+          [
+            work_package1,
+            work_package2,
+            work_package2bis,
+            work_package3,
+            work_package4,
+            work_package5
+          ]
+        )
+      end
+
+      it 'returns the same ascii representation without properties information' do
+        expect(chart.to_s).to eq(<<~CHART.chomp)
+          days         |    MTWTFSS  |
+          main         |    XX       |
+          working_days |     XXXX..X |
+          all_days     |     XXXXXXX |
+          start_only   | [           |
+          due_only     |      ]      |
+          no_dates     |             |
+        CHART
+      end
+    end
+  end
+end

spec/support_spec/schedule_helpers/example_methods_spec.rb

@@ -0,0 +1,153 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'spec_helper'
+
+describe ScheduleHelpers::ExampleMethods do
+  include ActiveSupport::Testing::TimeHelpers
+
+  create_shared_association_defaults_for_work_package_factory
+
+  let(:fake_today) { Date.new(2022, 6, 16) } # Thursday 16 June 2022
+  let(:monday) { Date.new(2022, 6, 20) } # Monday 20 June
+  let(:tuesday) { Date.new(2022, 6, 21) }
+  let(:wednesday) { Date.new(2022, 6, 22) }
+  let(:thursday) { Date.new(2022, 6, 23) }
+  let(:friday) { Date.new(2022, 6, 24) }
+  let(:saturday) { Date.new(2022, 6, 25) }
+  let(:sunday) { Date.new(2022, 6, 26) }
+
+  describe 'expect_schedule' do
+    let_schedule(<<~CHART)
+            | MTWTFSS |
+      main  | XX      |
+      other |   XXX   |
+    CHART
+
+    it 'checks the work packages properties according to the given work packages and chart representation' do
+      expect do
+        expect_schedule([main, other], <<~CHART)
+                | MTWTFSS |
+          main  | XX      |
+          other |   XXX   |
+        CHART
+      end.not_to raise_error
+    end
+
+    it 'raises an error if start_date is wrong' do
+      expect do
+        expect_schedule([main], <<~CHART)
+                | MTWTFSS |
+          main  |  X      |
+        CHART
+      end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+    end
+
+    it 'raises an error if due_date is wrong' do
+      expect do
+        expect_schedule([main], <<~CHART)
+                | MTWTFSS |
+          main  | XXXXX   |
+        CHART
+      end.to raise_error(RSpec::Expectations::ExpectationNotMetError)
+    end
+
+    it 'raises an error if no work package exists for a given name' do
+      expect do
+        expect_schedule([main], <<~CHART)
+                  | MTWTFSS |
+          unknown | XX      |
+        CHART
+      end.to raise_error(ArgumentError, "unable to find WorkPackage :unknown")
+    end
+
+    it 'checks against the given work packages rather than the ones from the let! definitions' do
+      expect do
+        expect_schedule([], <<~CHART)
+                | MTWTFSS |
+          main  | XX      |
+        CHART
+      end.not_to raise_error
+    end
+
+    it 'uses the work package from the let! definitions if it is not given as parameter' do
+      a_modified_instance_of_main = WorkPackage.find(main.id)
+      a_modified_instance_of_main.due_date += 2.days
+      expect do
+        expect_schedule([main], <<~CHART)
+                | MTWTFSS |
+          main  | XX      |
+        CHART
+      end.not_to raise_error
+      expect do
+        expect_schedule([a_modified_instance_of_main], <<~CHART)
+                | MTWTFSS |
+          main  | XXXX    |
+        CHART
+      end.not_to raise_error
+      expect do
+        expect_schedule([], <<~CHART)
+                | MTWTFSS |
+          main  | XX      |
+        CHART
+      end.not_to raise_error
+    end
+  end
+
+  describe 'change_schedule' do
+    before do
+      travel_to(fake_today)
+    end
+
+    it 'applies dates changes to a group of work packages from a visual chart representation' do
+      main = build_stubbed(:work_package, subject: 'main')
+      second = build_stubbed(:work_package, subject: 'second')
+      change_schedule([main, second], <<~CHART)
+        days   | MTWTFSS |
+        main   | XX      |
+        second |    XX   |
+      CHART
+      expect(main.start_date).to eq(monday)
+      expect(main.due_date).to eq(tuesday)
+      expect(second.start_date).to eq(thursday)
+      expect(second.due_date).to eq(friday)
+    end
+
+    it 'does not save changes' do
+      main = create(:work_package, subject: 'main')
+      expect(main.persisted?).to be(true)
+      expect(main.has_changes_to_save?).to be(false)
+      change_schedule([main], <<~CHART)
+        days   | MTWTFSS |
+        main   | XX      |
+      CHART
+      expect(main.has_changes_to_save?).to be(true)
+      expect(main.changes).to eq('start_date' => [nil, monday], 'due_date' => [nil, tuesday])
+    end
+  end
+end

spec/support_spec/schedule_helpers/let_schedule_spec.rb

@@ -0,0 +1,100 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'spec_helper'
+
+describe ScheduleHelpers::LetSchedule do
+  include ActiveSupport::Testing::TimeHelpers
+
+  create_shared_association_defaults_for_work_package_factory
+
+  let(:fake_today) { Date.new(2022, 6, 16) } # Thursday 16 June 2022
+  let(:monday) { Date.new(2022, 6, 20) } # Monday 20 June
+  let(:tuesday) { Date.new(2022, 6, 21) }
+  let(:wednesday) { Date.new(2022, 6, 22) }
+  let(:thursday) { Date.new(2022, 6, 23) }
+  let(:friday) { Date.new(2022, 6, 24) }
+  let(:saturday) { Date.new(2022, 6, 25) }
+  let(:sunday) { Date.new(2022, 6, 26) }
+
+  describe 'let_schedule' do
+    let_schedule(<<~CHART)
+      days      | MTWTFSS |
+      main      | XX      |
+      follower  |   XXX   | follows main with delay 2
+      child     |         | child of main
+    CHART
+
+    it 'creates let! call for :schedule_chart which returns the chart' do
+      next_monday = (Time.zone.today..(Time.zone.today + 7.days)).find { |d| d.wday == 1 }
+      expect(schedule_chart.first_day).to eq(next_monday)
+    end
+
+    it 'creates let! calls for each work package' do
+      expect([main, follower, child]).to all(be_an_instance_of(WorkPackage))
+      expect([main, follower, child]).to all(be_persisted)
+      expect(main).to have_attributes(
+        subject: 'main',
+        start_date: schedule_chart.monday,
+        due_date: schedule_chart.monday + 1.day
+      )
+      expect(follower).to have_attributes(
+        subject: 'follower',
+        start_date: schedule_chart.monday + 2.days,
+        due_date: schedule_chart.monday + 4.days
+      )
+      expect(child).to have_attributes(
+        subject: 'child',
+        start_date: nil,
+        due_date: nil
+      )
+    end
+
+    it 'creates let! calls for follows relations between work packages' do
+      expect(follower.follows_relations.count).to eq(1)
+      expect(relation_follower_follows_main).to be_an_instance_of(Relation)
+      expect(relation_follower_follows_main.delay).to eq(2)
+    end
+
+    it 'creates parent / child relations' do
+      expect(child.parent).to eq(main)
+    end
+
+    context 'with additional attributes' do
+      let_schedule(<<~CHART, done_ratio: 50, schedule_manually: true)
+        days      | MTWTFSS |
+        main      | XX      |
+        follower  |   XXX   | follows main
+      CHART
+
+      it 'applies additional attributes to all created work packages' do
+        expect([main, follower]).to all(have_attributes(done_ratio: 50, schedule_manually: true))
+      end
+    end
+  end
+end