Fix divide by zero error for averages on an empty collection (#14)

veracross · Jun 26, 2020 · 921c15f · 921c15f
1 parent fe22c8e
commit 921c15f
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diff --git a/lib/data-table/table.rb b/lib/data-table/table.rb
@@ -423,6 +423,8 @@ def calculate_sum(collection, column_name)
     end
 
     def calculate_avg(collection, column_name)
+      return 0 if collection.empty?
+
       sum = calculate_sum(collection, column_name)
       sum / collection.size
     end

diff --git a/spec/table_spec.rb b/spec/table_spec.rb
@@ -138,6 +138,13 @@
       expect(data_table.render).to \
       eq(%{<table id='' class='data_table ' cellspacing='0' cellpadding='0'><caption></caption><thead><tr></tr></thead><tr><td class='empty_data_table' colspan='0'>#{text}</td></tr></table>})
     end
+
+    it "avoids dividing by zero" do
+      data_table.column :power_level
+      data_table.total :power_level, :avg, 0
+      data_table.calculate_totals!
+      expect(data_table.total_calculations).to eq([{:power_level=>0}])
+    end
   end
 
   context 'with a more complicated setup' do