Refactor output_pa.

app/models/pv_query.rb

@@ -63,19 +63,11 @@ def add_all_panels_outputs
   end
 
   # Formula is approximation. Cannot confirm accuracy of result yet.
-  # Untested because factory is not set up correctly.
   # http://math.stackexchange.com/questions/438766/volume-of-irregular-solid
   # @return [Float] volume under graph (Wh).
   def output_pa
-    total_volume = 0
     const = volume_constant
-    self.column_heights.each do |column|
-      # vol = 0.25 * length_of_insolation_reading *
-      #   readings_per_annual_increment * column.inject(:+)
-      total_volume += (const * column.inject(:+))
-    end
-    # convert to Wh
-    (total_volume * 3600).round
+    column_heights.reduce(0) { |a, col| a + (const * col.reduce(:+)) }.round
   end
 
   # TODO: check this formula!

spec/models/pv_query_spec.rb

@@ -82,9 +82,21 @@
     end
   end
 
-  # describe 'output_pa_array' do
+  # describe 'output_pa' do
   #   it "should return the volume under the graph" do
-  #     expect(pv_query.output_pa_array).to eq('1234')
+  #     expect(pv_query.output_pa).to eq(1789171)
+  #   end
+  # end
+
+  # describe 'column_heights' do
+  #   it "should return the volume under the graph" do
+  #     expect(pv_query.column_heights).to eq(6441016320)
+  #   end
+  # end
+  #
+  # describe 'volume_constant' do
+  #   it 'should return the correct constant' do
+  #     expect(pv_query.volume_constant).to eq(90.0)
   #   end
   # end