Convert specs to tests

#623

spec/models/invoice_spec.rb

@@ -51,20 +51,6 @@ describe Invoice do
       @invoice.seller_address.should == 'Paldiski mnt. 123, Tallinn'
     end
 
-    it 'should calculate sums correctly' do
-      @invoice = create(:invoice)
-      @invoice.vat_rate.should == BigDecimal.new('0.2')
-      @invoice.sum_without_vat.should == BigDecimal.new('300.0')
-      @invoice.vat.should == BigDecimal.new('60.0')
-      @invoice.sum.should == BigDecimal.new('360.0')
-
-      ii = @invoice.items.first
-      ii.item_sum_without_vat.should == BigDecimal.new('150.0')
-
-      ii = @invoice.items.last
-      ii.item_sum_without_vat.should == BigDecimal.new('150.0')
-    end
-
     it 'should cancel overdue invoices' do
       create(:invoice, created_at: Time.zone.now - 35.days, due_date: Time.zone.now - 30.days)
       Invoice.cancel_overdue_invoices

test/models/invoice_test.rb

@@ -8,4 +8,16 @@ class InvoiceTest < ActiveSupport::TestCase
   def test_valid
     assert @invoice.valid?
   end
+
+  def test_calculates_subtotal
+    assert_equal BigDecimal('15'), @invoice.sum_without_vat
+  end
+
+  def test_calculates_vat_amount
+    assert_equal BigDecimal('1.5'), @invoice.vat
+  end
+
+  def test_calculates_total
+    assert_equal BigDecimal('16.5'), @invoice.sum
+  end
 end