#434

backend/app/services/counts_pivot_layout.rb

@@ -28,6 +28,7 @@ class CountsPivotLayout
     result = []
     values.each_with_index do |tuple, index|
       result << { values: tuple, kind: 'data' }
+      # A group continuing on the next page closes only on its final page.
       following = values[index + 1] || next_values
       depths.reverse_each do |depth|
         prefix = tuple.first(depth)

backend/spec/services/counts_pivot_security_spec.rb

@@ -45,17 +45,28 @@ RSpec.describe 'Counts masked pivot contracts' do
   end
 
   it 'preserves monthly name subtotals and grand totals across pages' do
-    settings = { 'resource' => 'tags', 'rows' => 'created_at:month name_ja' }
+    settings = { 'resource' => 'tags', 'rows' => 'created_at:month name' }
     complete = result(admin, settings)
-    paged = result(admin, settings.merge('limit' => '1'))
     expect(complete[:group_count]).to eq(3)
     expect(grand(complete)).to eq(3)
-    expect(grand(paged)).to eq(3)
-    subtotal = paged[:pivot_totals].find do |cell|
-      cell[:row] == ['2023-01'] && cell[:column].empty?
+    (1..3).each do |page|
+      paged = result(admin, settings.merge('limit' => '1', 'page' => page.to_s))
+      expect(grand(paged)).to eq(3)
+      subtotal = paged[:pivot_totals].find do |cell|
+        cell[:row] == ['2023-01'] && cell[:column].empty?
+      end
+      headers = paged[:row_headers].select { _1[:kind] == 'subtotal' }
+      if page == 3
+        expect(headers.map { _1[:values] }).to eq([['2023-01']])
+        expect(subtotal).not_to be_nil
+        expect(subtotal[:count]).to eq(3)
+      else
+        expect(headers).to eq([])
+        expect(subtotal).to be_nil
+      end
+      expect(paged[:cells].sum { _1[:count] }).to eq(1)
+      expect(paged[:group_count]).to eq(3)
     end
-    expect(subtotal[:count]).to eq(3)
-    expect(paged[:cells].sum { _1[:count] }).to eq(1)
   end
 
   it 'preserves five tag occurrences after merging private tags and across pages' do