Add Budget#formatted_amount unit test

spec/models/budget_spec.rb

@@ -228,4 +228,38 @@ describe Budget do
       expect(finished_phase.prev_phase).to eq(reviewing_ballots_phase)
     end
   end
+
+  describe "#formatted_amount" do
+    after do
+      I18n.locale = :en
+    end
+
+    it "correctly formats Euros with Spanish" do
+      budget.update(currency_symbol: '€')
+      I18n.locale = :es
+
+      expect(budget.formatted_amount(1000.00)).to eq ('1.000 €')
+    end
+
+    it "correctly formats Dollars with Spanish" do
+      budget.update(currency_symbol: '$')
+      I18n.locale = :es
+
+      expect(budget.formatted_amount(1000.00)).to eq ('1.000 $')
+    end
+
+    it "correctly formats Dollars with English" do
+      budget.update(currency_symbol: '$')
+      I18n.locale = :en
+
+      expect(budget.formatted_amount(1000.00)).to eq ('$1,000')
+    end
+
+    it "correctly formats Euros with English" do
+      budget.update(currency_symbol: '€')
+      I18n.locale = :en
+
+      expect(budget.formatted_amount(1000.00)).to eq ('€1,000')
+    end
+  end
 end