Fix vat rate

#623

app/models/invoice.rb

@@ -32,9 +32,11 @@ class Invoice < ActiveRecord::Base
   validates :vat_rate, numericality: { greater_than_or_equal_to: 0, less_than: 100 },
             allow_nil: true
 
-  before_create :set_invoice_number, :check_vat
+  after_initialize :apply_defaults
+  before_create :set_invoice_number
 
-  before_save   :check_vat
+  attribute :vat_rate, ::Type::VATRate.new
+  attr_readonly :vat_rate
 
   def set_invoice_number
     last_no = Invoice.order(number: :desc).where('number IS NOT NULL').limit(1).pluck(:number).first
@@ -52,12 +54,6 @@ class Invoice < ActiveRecord::Base
     false
   end
 
-  def check_vat
-    if buyer.country_code != 'EE' && buyer.vat_no.present?
-      self.vat_rate = 0
-    end
-  end
-
   before_save -> { self.sum_cache = sum }
 
   class << self
@@ -159,10 +155,17 @@ class Invoice < ActiveRecord::Base
   end
 
   def vat
+    return 0 unless vat_rate
     (sum_without_vat * vat_rate).round(2)
   end
 
   def sum
     (sum_without_vat + vat).round(2)
   end
+
+  private
+
+  def apply_defaults
+    self.vat_rate = buyer.effective_vat_rate unless vat_rate
+  end
 end

app/models/registrar.rb

@@ -18,8 +18,8 @@ class Registrar < ActiveRecord::Base
   validates :accounting_customer_code, presence: true
   validates :language, presence: true
 
-  validates :vat_rate, presence: true, if: :vat_rate_required?
+  validates :vat_rate, presence: true, if: 'foreign_vat_payer? && vat_no.blank?'
-  validates :vat_rate, absence: true, if: :local_vat_payer?
+  validates :vat_rate, absence: true, if: :home_vat_payer?
   validates :vat_rate, absence: true, if: 'foreign_vat_payer? && vat_no?'
   validates :vat_rate, numericality: { greater_than_or_equal_to: 0, less_than: 100 },
             allow_nil: true
@@ -56,22 +56,11 @@ class Registrar < ActiveRecord::Base
   # rubocop:disable Metrics/MethodLength
   # rubocop:disable Metrics/AbcSize
   def issue_prepayment_invoice(amount, description = nil)
-    vat_rate = if local_vat_payer?
-                 Registry.instance.vat_rate
-               else
-                 if vat_no.blank?
-                   self.vat_rate
-                 else
-                   nil
-                 end
-               end
-
     invoices.create(
       due_date: (Time.zone.now.to_date + Setting.days_to_keep_invoices_active.days).end_of_day,
       payment_term: 'prepayment',
       description: description,
       currency: 'EUR',
-      vat_rate: vat_rate,
       seller_name: Setting.registry_juridical_name,
       seller_reg_no: Setting.registry_reg_no,
       seller_iban: Setting.registry_iban,
@@ -157,6 +146,14 @@ class Registrar < ActiveRecord::Base
     end
   end
 
+  def effective_vat_rate
+    if home_vat_payer?
+      Registry.instance.vat_rate
+    else
+      vat_rate
+    end
+  end
+
   private
 
   def set_defaults
@@ -188,15 +185,11 @@ class Registrar < ActiveRecord::Base
     end
   end
 
-  def local_vat_payer?
+  def home_vat_payer?
     country == Registry.instance.legal_address_country
   end
 
   def foreign_vat_payer?
-    !local_vat_payer?
+    !home_vat_payer?
-  end
-
-  def vat_rate_required?
-    foreign_vat_payer? && vat_no.blank?
   end
 end

app/models/type/vat_rate.rb

@@ -1,19 +1,11 @@
 module Type
-  class VATRate < ActiveRecord::Type::Value
+  class VATRate < ActiveRecord::Type::Decimal
-    def type_cast_from_user(value)
-      if value.blank?
-        nil
-      else
-        super
-      end
-    end
-
     def type_cast_from_database(value)
-      BigDecimal(value) * 100 if value
+      super * 100 if value
     end
 
     def type_cast_for_database(value)
-      BigDecimal(value) / 100.0 if value
+      super / 100.0 if value
     end
   end
 end

test/fixtures/invoices.yml

@@ -4,6 +4,7 @@ DEFAULTS: &DEFAULTS
   currency: EUR
   seller_name: John Doe
   seller_iban: 1234
+  buyer: bestnames
   buyer_name: Jane Doe
   vat_rate: 0.2
 

test/fixtures/registrars.yml

@@ -17,7 +17,8 @@ goodnames:
   reg_no: 12345
   code: goodnames
   email: info@goodnames.test
-  country_code: US
+  country_code: DE
+  vat_no: DE123456789
   accounting_customer_code: goodnames
   language: en
 

test/models/invoice/vat_rate_test.rb

@@ -0,0 +1,51 @@
+require 'test_helper'
+
+class InvoiceVATRateTest < ActiveSupport::TestCase
+  def setup
+    @invoice = invoices(:valid)
+  end
+
+  def test_valid_without_vat_rate
+    @invoice.vat_rate = nil
+    assert @invoice.valid?
+  end
+
+  def test_vat_rate_validation
+    @invoice.vat_rate = -1
+    assert @invoice.invalid?
+
+    @invoice.vat_rate = 0
+    assert @invoice.valid?
+
+    @invoice.vat_rate = 99.9
+    assert @invoice.valid?
+
+    @invoice.vat_rate = 100
+    assert @invoice.invalid?
+  end
+
+  def test_serializes_and_deserializes_vat_rate
+    invoice = @invoice.dup
+    invoice.invoice_items = @invoice.invoice_items
+    invoice.vat_rate = BigDecimal('25.5')
+    invoice.save!
+    invoice.reload
+    assert_equal BigDecimal('25.5'), invoice.vat_rate
+  end
+
+  def test_vat_rate_defaults_to_effective_vat_rate_of_a_registrar
+    registrar = registrars(:bestnames)
+
+    registrar.stub(:effective_vat_rate, 55) do
+      invoice = Invoice.new(buyer: registrar)
+      assert_equal 55, invoice.vat_rate
+    end
+  end
+
+  def test_vat_rate_cannot_be_updated
+    @invoice.vat_rate = 21
+    @invoice.save!
+    @invoice.reload
+    refute_equal 21, @invoice.vat_rate
+  end
+end

test/models/invoice_test.rb

@@ -8,23 +8,4 @@ class InvoiceTest < ActiveSupport::TestCase
   def test_valid
     assert @invoice.valid?
   end
-
-  def test_valid_without_vat_rate
-    @invoice.vat_rate = nil
-    assert @invoice.valid?
-  end
-
-  def test_vat_rate_validation
-    @invoice.vat_rate = -1
-    assert @invoice.invalid?
-
-    @invoice.vat_rate = 1
-    assert @invoice.valid?
-
-    @invoice.vat_rate = 99.9
-    assert @invoice.valid?
-
-    @invoice.vat_rate = 100
-    assert @invoice.invalid?
-  end
 end

test/models/registrar/vat_test.rb

@@ -13,28 +13,6 @@ class RegistrarVATTest < ActiveSupport::TestCase
     assert @registrar.valid?
   end
 
-  def test_requires_vat_rate_when_registrar_is_foreign_vat_payer_and_vat_no_is_absent
-    @registrar.vat_no = ''
-
-    Registry.instance.stub(:legal_address_country, Country.new('GB')) do
-      @registrar.vat_rate = ''
-      assert @registrar.invalid?
-      assert @registrar.errors.added?(:vat_rate, :blank)
-
-      @registrar.vat_rate = -1
-      assert @registrar.invalid?
-
-      @registrar.vat_rate = 1
-      assert @registrar.valid?
-
-      @registrar.vat_rate = 99.9
-      assert @registrar.valid?
-
-      @registrar.vat_rate = 100
-      assert @registrar.invalid?
-    end
-  end
-
   def test_vat_is_not_applied_when_registrar_is_local_vat_payer
     @registrar.vat_rate = 1
     assert @registrar.invalid?
@@ -43,30 +21,57 @@ class RegistrarVATTest < ActiveSupport::TestCase
     assert @registrar.valid?
   end
 
+  def test_requires_vat_rate_when_registrar_is_foreign_vat_payer_and_vat_no_is_absent
+    @registrar.country_code = 'DE'
+    @registrar.vat_no = ''
+
+    @registrar.vat_rate = ''
+    assert @registrar.invalid?
+    assert @registrar.errors.added?(:vat_rate, :blank)
+  end
+
   def test_vat_is_not_applied_when_registrar_is_foreign_vat_payer_and_vat_no_is_present
+    @registrar.country_code = 'DE'
     @registrar.vat_no = 'valid'
 
-    Registry.instance.stub(:legal_address_country, Country.new('GB')) do
+    @registrar.vat_rate = 1
-      @registrar.vat_rate = 1
+    assert @registrar.invalid?
-      assert @registrar.invalid?
 
-      @registrar.vat_rate = nil
+    @registrar.vat_rate = nil
-      assert @registrar.valid?
+    assert @registrar.valid?
-    end
+  end
+
+  def test_vat_rate_validation
+    @registrar.country_code = 'DE'
+    @registrar.vat_no = ''
+
+    @registrar.vat_rate = -1
+    assert @registrar.invalid?
+
+    @registrar.vat_rate = 0
+    assert @registrar.valid?
+
+    @registrar.vat_rate = 99.9
+    assert @registrar.valid?
+
+    @registrar.vat_rate = 100
+    assert @registrar.invalid?
   end
 
   def test_serializes_and_deserializes_vat_rate
-    @registrar.vat_rate = '25.5'
+    @registrar.country_code = 'DE'
-
+    @registrar.vat_rate = BigDecimal('25.5')
-    Registry.instance.stub(:legal_address_country, Country.new('GB')) do
+    @registrar.save!
-      @registrar.save!
-    end
-
     @registrar.reload
-    assert_equal 25.5, @registrar.vat_rate
+    assert_equal BigDecimal('25.5'), @registrar.vat_rate
   end
 
-  def test_treats_empty_vat_rate_as_absent
+  def test_parses_vat_rate_as_a_string
+    @registrar.vat_rate = '25.5'
+    assert_equal BigDecimal('25.5'), @registrar.vat_rate
+  end
+
+  def test_treats_empty_vat_rate_as_nil
     @registrar.vat_rate = ''
     assert_nil @registrar.vat_rate
   end