adds specs for budged model

spec/models/budget_spec.rb

@@ -1,8 +1,10 @@
 require 'rails_helper'
 
 describe Budget do
-  it "validates the phase" do
-    budget = create(:budget)
+  describe "phase" do
+    let(:budget) { create(:budget) }
+
+    it "is validated" do
       Budget::VALID_PHASES.each do |phase|
         budget.phase = phase
         expect(budget).to be_valid
@@ -11,5 +13,40 @@ describe Budget do
       budget.phase = 'inexisting'
       expect(budget).to_not be_valid
     end
+
+    it "produces auxiliary methods" do
+      budget.phase = "on_hold"
+      expect(budget).to be_on_hold
+
+      budget.phase = "accepting"
+      expect(budget).to be_accepting
+
+      budget.phase = "selecting"
+      expect(budget).to be_selecting
+
+      budget.phase = "balloting"
+      expect(budget).to be_balloting
+
+      budget.phase = "finished"
+      expect(budget).to be_finished
+    end
+  end
+
+  describe "heading_price" do
+    let(:budget) { create(:budget, price: 1000) }
+
+    it "returns the budget price if no heading is provided" do
+      expect(budget.heading_price(nil)).to eq(1000)
+    end
+
+    it "returns the heading price if the heading provided is part of the budget" do
+      heading = create(:budget_heading, price: 100, budget: budget)
+      expect(budget.heading_price(heading)).to eq(100)
+    end
+
+    it "returns -1 if the heading provided is not part of the budget" do
+      expect(budget.heading_price(create(:budget_heading))).to eq(-1)
+    end
+  end
 end