From 921c15fa6de8befc63f520737b4f62f86193f992 Mon Sep 17 00:00:00 2001
From: Andrew Harper <andrew.harper@veracross.com>
Date: Fri, 26 Jun 2020 09:28:17 -0400
Subject: [PATCH] Fix divide by zero error for averages on an empty collection
 (#14)

---
 lib/data-table/table.rb | 2 ++
 spec/table_spec.rb      | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/lib/data-table/table.rb b/lib/data-table/table.rb
index 2da8f33..9da2104 100644
--- 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
index 021fe83..96284c8 100644
--- 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