adds budget result specs

spec/models/budget/result_spec.rb

@@ -0,0 +1,35 @@
+require 'rails_helper'
+
+describe Budget::Result, :focus do
+
+  describe "calculate_winners" do
+    let(:budget) { create(:budget) }
+    let(:group) { create(:budget_group, budget: budget) }
+    let(:heading) { create(:budget_heading, group: group, price: 1000) }
+
+    it "calculates a budget's winner investments" do
+      investment1 = create(:budget_investment, :selected, heading: heading, price: 200, ballot_lines_count: 900)
+      investment2 = create(:budget_investment, :selected, heading: heading, price: 300, ballot_lines_count: 800)
+      investment3 = create(:budget_investment, :selected, heading: heading, price: 500, ballot_lines_count: 700)
+      investment4 = create(:budget_investment, :selected, heading: heading, price: 100, ballot_lines_count: 600)
+
+      result = Budget::Result.new(budget, heading)
+      result.calculate_winners
+
+      expect(result.winners).to eq([investment1, investment2, investment3])
+    end
+
+    it "resets winners before recalculating" do
+      investment1 = create(:budget_investment, :selected, heading: heading, price: 200, ballot_lines_count: 900, winner: true)
+      investment2 = create(:budget_investment, :selected, heading: heading, price: 300, ballot_lines_count: 800, winner: true)
+      investment3 = create(:budget_investment, :selected, heading: heading, price: 500, ballot_lines_count: 700, winner: true)
+      investment4 = create(:budget_investment, :selected, heading: heading, price: 100, ballot_lines_count: 600, winner: true)
+
+      result = Budget::Result.new(budget, heading)
+      result.calculate_winners
+
+      expect(result.winners).to eq([investment1, investment2, investment3])
+    end
+  end
+
+end