Avoid crashing on Ruby 2.4 for numeric strings (#470)

Author: flori

lib/split/dashboard/helpers.rb

@@ -18,7 +18,11 @@ def number_to_percentage(number, precision = 2)
     end
 
     def round(number, precision = 2)
-      BigDecimal.new(number.to_s).round(precision).to_f
+      begin
+        BigDecimal.new(number.to_s)
+      rescue ArgumentError
+        BigDecimal.new(0)
+      end.round(precision).to_f
     end
 
     def confidence_level(z_score)

spec/dashboard_helpers_spec.rb

@@ -24,5 +24,19 @@
       expect(confidence_level(2.58)).to eq('99% confidence')
       expect(confidence_level(3.00)).to eq('99% confidence')
     end
+
+    describe '#round' do
+      it 'can round number strings' do
+        expect(round('3.1415')).to eq BigDecimal.new('3.14')
+      end
+
+      it 'can round number strings for precsion' do
+        expect(round('3.1415', 1)).to eq BigDecimal.new('3.1')
+      end
+
+      it 'can handle invalid number strings' do
+        expect(round('N/A')).to be_zero
+      end
+    end
   end
 end