Report rules can define a summary row

lib/open_food_network/reports/rule.rb

@@ -1,3 +1,5 @@
+require 'open_food_network/reports/row'
+
 module OpenFoodNetwork::Reports
   class Rule
     attr_reader :next
@@ -10,13 +12,20 @@ module OpenFoodNetwork::Reports
       @sort = block
     end
 
+    def summary_row(&block)
+      @summary_row = Row.new
+      @summary_row.instance_eval(&block)
+    end
+
     def organise(&block)
       @next = Rule.new
       @next.instance_eval &block
     end
 
     def to_h
-      {group_by: @group, sort_by: @sort}
+      h = {group_by: @group, sort_by: @sort}
+      h.merge!({summary_columns: @summary_row.to_a}) if @summary_row
+      h
     end
   end
 end

spec/lib/open_food_network/reports/report_spec.rb

@@ -18,6 +18,11 @@ module OpenFoodNetwork::Reports
       organise do
         group { |o| o[:three] }
         sort  { |o| o[:four] }
+
+        summary_row do
+          column { |o| o[:one] }
+          column { |o| o[:four] }
+        end
       end
     end
   end
@@ -43,6 +48,7 @@ module OpenFoodNetwork::Reports
       let(:sort_by) { rules_head.to_h[:sort_by] }
       let(:next_group_by) { rules_head.next.to_h[:group_by] }
       let(:next_sort_by) { rules_head.next.to_h[:sort_by] }
+      let(:next_summary_columns) { rules_head.next.to_h[:summary_columns] }
 
       it "constructs the head of the rules list" do
         group_by.call(data).should == 1
@@ -53,6 +59,11 @@ module OpenFoodNetwork::Reports
         next_group_by.call(data).should == 3
         next_sort_by.call(data).should == 4
       end
+
+      it "constructs summary columns for rules" do
+        next_summary_columns[0].call(data).should == 1
+        next_summary_columns[1].call(data).should == 4
+      end
     end
   end
 end

spec/lib/open_food_network/reports/rule_spec.rb

@@ -19,5 +19,18 @@ module OpenFoodNetwork::Reports
       rule.organise &proc
       rule.next.should be_a Rule
     end
+
+    it "can define a summary row and return it in a hash" do
+      rule.summary_row do
+        column {}
+        column {}
+        column {}
+      end
+
+      rule.to_h[:summary_columns].count.should == 3
+      rule.to_h[:summary_columns][0].should be_a Proc
+      rule.to_h[:summary_columns][1].should be_a Proc
+      rule.to_h[:summary_columns][2].should be_a Proc
+    end
   end
 end