[#42761] Date formatting in XLS export from Cost Report is wrong

https://community.openproject.org/work_packages/42761

modules/reporting/lib/open_project/reporting/cost_entry_xls_table.rb

@@ -41,7 +41,8 @@ class OpenProject::Reporting::CostEntryXlsTable < OpenProject::XlsExport::XlsVie
 
   def build_cost_rows
     sorted_results.each do |result|
-      spreadsheet.add_row(cost_row(result))
+      row = spreadsheet.add_row(cost_row(result))
+      row.set_format 0, date_format
     end
   end
 
@@ -73,7 +74,7 @@ class OpenProject::Reporting::CostEntryXlsTable < OpenProject::XlsExport::XlsVie
   end
 
   def cost_main_columns(result)
-    main_cols = [show_field(:spent_on, result.fields["spent_on"])]
+    main_cols = [result.fields["spent_on"].to_date]
     main_cols.concat cost_main_times_columns(result) if with_times_column?
     main_cols
   end

modules/reporting/spec/features/export_cost_report_spec.rb

@@ -33,7 +33,7 @@ require_relative "support/pages/cost_report_page"
 
 RSpec.describe "Cost reports XLS export", :js do
   shared_let(:project) { create(:project) }
-  shared_let(:user) { create(:admin) }
+  shared_let(:user) { create(:admin, preferences: { time_zone: "UTC" }) }
   shared_let(:cost_type) { create(:cost_type, name: "Post-war", unit: "cap", unit_plural: "caps") }
   shared_let(:work_package) { create(:work_package, project:, subject: "Some task") }
   shared_let(:cost_entry) do
@@ -72,9 +72,13 @@ RSpec.describe "Cost reports XLS export", :js do
     DownloadList.clear
   end
 
-  def expect_custom_cost_entry(cost_entry_row)
+  def excel_float_to_date(excel_float)
+    (DateTime.new(1899, 12, 30) + excel_float).to_date
+  end
+
+  def expect_custom_cost_entry(cost_entry_row, entry)
     date, user_ref, _, wp_ref, _, project_ref, costs, type, = cost_entry_row
-    expect(date).to eq(cost_entry.spent_on.iso8601)
+    expect(excel_float_to_date(date)).to eq(entry.spent_on)
     expect(user_ref).to eq(user.name)
     expect(wp_ref).to include "Some task"
     expect(project_ref).to eq project.name
@@ -84,7 +88,7 @@ RSpec.describe "Cost reports XLS export", :js do
 
   def expect_labor_cost_entry(cost_entry_row, entry)
     date, user_ref, _, wp_ref, _, project_ref, costs, type, = cost_entry_row
-    expect(date).to eq(entry.spent_on.iso8601)
+    expect(excel_float_to_date(date)).to eq(entry.spent_on)
     expect(user_ref).to eq(user.name)
     expect(wp_ref).to include "Some task"
     expect(project_ref).to eq project.name
@@ -94,7 +98,7 @@ RSpec.describe "Cost reports XLS export", :js do
 
   def expect_time_entry(time_entry_row, entry, start_time_value, end_time_value)
     date, start_time, end_time, user_ref, _, wp_ref, _, project_ref, costs, type, = time_entry_row
-    expect(date).to eq(entry.spent_on.iso8601)
+    expect(excel_float_to_date(date)).to eq(entry.spent_on)
     expect(start_time).to eq start_time_value
     expect(end_time).to eq end_time_value
     expect(user_ref).to eq(user.name)
@@ -111,7 +115,7 @@ RSpec.describe "Cost reports XLS export", :js do
   def expect_cost_entries_sheet
     title, _, cost_entry_row, time_entry_row, time_entry_long_row = subject.first.rows
     expect_sheet_title title
-    expect_custom_cost_entry cost_entry_row
+    expect_custom_cost_entry cost_entry_row, cost_entry
     expect_labor_cost_entry time_entry_row, time_entry
     expect_labor_cost_entry time_entry_long_row, time_entry_long
   end
@@ -130,9 +134,9 @@ RSpec.describe "Cost reports XLS export", :js do
   end
 
   def expect_custom_type_entries_sheet
-    title, _, cost_entry = subject.third.rows
+    title, _, cost_entry_row = subject.third.rows
     expect_sheet_title title
-    expect_custom_cost_entry cost_entry
+    expect_custom_cost_entry cost_entry_row, cost_entry
   end
 
   def export_xls

modules/xls_export/lib/open_project/xls_export/xls_views.rb

@@ -69,6 +69,14 @@ class OpenProject::XlsExport::XlsViews
     "0.00"
   end
 
+  def date_format
+    @date_format ||= Spreadsheet::Format.new(
+      number_format: "yyyy-mm-dd",
+      horizontal_align: :left,
+      vertical_align: :top
+    )
+  end
+
   def project_representation(value)
     ar_presentation(Project, value, &:name)
   end