[59539] Migration: set lag for follows relations

To preserve dates, a lag is set for follows relations when both the
predecessor and the follower have dates.

app/workers/work_packages/automatic_mode/migrate_values_job.rb

@@ -32,6 +32,7 @@ def perform
       change_scheduling_mode_to_manual
       change_scheduling_mode_to_automatic_for_followers
       change_scheduling_mode_to_automatic_for_parents
+      set_lags_for_follows_relations
       copy_values_to_work_packages_and_update_journals
     end
   end
@@ -97,6 +98,19 @@ def change_scheduling_mode_to_automatic_for_parents
     SQL
   end
 
+  def set_lags_for_follows_relations
+    execute(<<~SQL.squish)
+      UPDATE relations
+      SET lag = COALESCE(wp_succ.start_date, wp_succ.due_date) - COALESCE(wp_pred.due_date, wp_pred.start_date) - 1
+      FROM work_packages wp_pred, work_packages wp_succ
+      WHERE relations.relation_type = 'follows'
+        AND relations.to_id = wp_pred.id
+        AND relations.from_id = wp_succ.id
+        AND COALESCE(wp_succ.start_date, wp_succ.due_date) IS NOT NULL
+        AND COALESCE(wp_pred.due_date, wp_pred.start_date) IS NOT NULL
+    SQL
+  end
+
   def copy_values_to_work_packages_and_update_journals
     updated_work_package_ids = copy_values_to_work_packages
     create_journals_for_updated_work_packages(updated_work_package_ids)

spec/migrations/update_scheduling_mode_and_lags_spec.rb

@@ -154,4 +154,53 @@
       expect(child).to be_schedule_manually
     end
   end
+
+  context "for 2 work packages following each other with distant dates" do
+    let_work_packages(<<~TABLE)
+      subject       | MTWTFSS | properties
+      predecessor 1 | XX      |
+      follower 1    |     XX  | follows predecessor 1
+
+      # only start dates
+      predecessor 2 |  [      |
+      follower 2    |     [   | follows predecessor 2
+
+      # only due dates
+      predecessor 3 |  ]      |
+      follower 3    |     ]   | follows predecessor 3 with lag 1
+    TABLE
+
+    it "sets a lag to the relation to ensure the distance is kept" do
+      run_migration
+
+      expect(follower1).to be_schedule_automatically
+      relations = _table.relations.map(&:reload)
+      expect(relations.map(&:lag)).to all(eq(2))
+    end
+  end
+
+  context "for 2 work packages following each other with missing dates" do
+    let_work_packages(<<~TABLE)
+      subject       | MTWTFSS | properties
+      # only predecessor has dates
+      predecessor 1 | XX      |
+      follower 1    |         | follows predecessor 1
+
+      # only successor has dates
+      predecessor 2 |         |
+      follower 2    |     XX  | follows predecessor 2
+
+      # none have dates
+      predecessor 3 |         |
+      follower 3    |         | follows predecessor 3 with lag 1
+    TABLE
+
+    it "does not change the existing lag" do
+      run_migration
+
+      expect(follower1).to be_schedule_automatically
+      relations = _table.relations.map(&:reload)
+      expect(relations.map(&:lag)).to eq([0, 0, 1])
+    end
+  end
 end

spec/support/table_helpers/column_type/properties.rb

@@ -73,7 +73,7 @@ def relations_for_raw_value(raw_value)
 
       def parse_property(property)
         case property
-        when /^follows (\w+)(?: with lag (\d+))?/
+        when /^follows (.+?)(?: with lag (\d+))?\s*$/
           {
             relations: {
               raw: property,

spec/support/table_helpers/table.rb

@@ -28,8 +28,9 @@
 
 module TableHelpers
   class Table
-    def initialize(work_packages_by_identifier)
+    def initialize(work_packages_by_identifier, relations)
       @work_packages_by_identifier = work_packages_by_identifier
+      @relations = relations
     end
 
     def work_package(name)
@@ -41,6 +42,10 @@ def work_packages
       @work_packages_by_identifier.values
     end
 
+    def relations
+      @relations
+    end
+
     private
 
     def normalize_name(name)

spec/support/table_helpers/table_data.rb

@@ -79,8 +79,8 @@ def work_package_identifiers
     end
 
     def create_work_packages
-      work_packages_by_identifier = Factory.new(self).create
-      Table.new(work_packages_by_identifier)
+      work_packages_by_identifier, relations = Factory.new(self).create
+      Table.new(work_packages_by_identifier, relations)
     end
 
     def order_like!(other_table)
@@ -93,11 +93,14 @@ def order_like!(other_table)
     end
 
     class Factory
-      attr_reader :table_data, :work_packages_by_identifier
+      include Identifier
+
+      attr_reader :table_data, :work_packages_by_identifier, :relations
 
       def initialize(table_data)
         @table_data = table_data
         @work_packages_by_identifier = {}
+        @relations = []
       end
 
       def create
@@ -108,7 +111,7 @@ def create
         table_data.work_package_identifiers.each do |identifier| # rubocop:disable Style/CombinableLoops
           create_follows_relations(identifier)
         end
-        work_packages_by_identifier
+        [work_packages_by_identifier, relations]
       end
 
       def create_work_package(identifier)
@@ -123,11 +126,10 @@ def create_work_package(identifier)
       end
 
       def create_follows_relations(identifier)
-        relations = work_package_relations(identifier)
-        relations.each do |relation|
-          predecessor = work_packages_by_identifier[relation[:predecessor].to_sym]
+        work_package_relations(identifier).each do |relation|
+          predecessor = find_work_package_by_name(relation[:predecessor])
           follower = work_packages_by_identifier[identifier]
-          FactoryBot.create(
+          relations << FactoryBot.create(
             :follows_relation,
             from: follower,
             to: predecessor,
@@ -136,6 +138,16 @@ def create_follows_relations(identifier)
         end
       end
 
+      def find_work_package_by_name(name)
+        identifier = to_identifier(name)
+        work_package = work_packages_by_identifier[identifier]
+        if work_package.nil?
+          raise "Work package with name #{name.inspect} (identifier: #{identifier.inspect}) not found. " \
+                "Available work package identifiers: #{work_packages_by_identifier.keys}."
+        end
+        work_package
+      end
+
       def lookup_parent(identifier)
         if identifier
           @work_packages_by_identifier[identifier] || create_work_package(identifier)