[#4410] Replace Payment Terms with an Enumeration

Instead of using a hard coded value for Payment Terms, they will use
Redmine's Enumeration table.  This provides an admin gui to managing
the value as well as ordering them.

test/unit/payment_term_test.rb

@@ -0,0 +1,40 @@
+require File.dirname(__FILE__) + '/../test_helper'
+
+class PaymentTermTest < ActiveSupport::TestCase
+  include Redmine::I18n
+
+  should_have_many(:contracts)
+  
+  should "be a subclass of Enumeration" do
+    assert_equal Enumeration, PaymentTerm.superclass
+  end
+
+  context "#option_name" do
+    should "be Payment Terms" do
+      assert_equal "Payment Terms", l(PaymentTerm.new.option_name)
+    end
+  end
+
+  context "#objects_count" do
+    should "count the number of contracts with this payment term" do
+      @payment_term = PaymentTerm.generate!(:type => 'PaymentTerm')
+      Contract.generate!(:payment_term => @payment_term)
+      Contract.generate!(:payment_term => @payment_term)
+
+      assert_equal 2, @payment_term.objects_count
+    end
+  end
+
+  context "#transfer_relations" do
+    should "update all contracts to use a new PaymentTerm" do
+      @old_payment_term = PaymentTerm.generate!(:type => 'PaymentTerm')
+      @new_payment_term = PaymentTerm.generate!(:type => 'PaymentTerm')
+      @contract1 = Contract.generate!(:payment_term => @old_payment_term)
+      @contract2 = Contract.generate!(:payment_term => @old_payment_term)
+
+      @old_payment_term.transfer_relations(@new_payment_term)
+      assert_equal @new_payment_term, @contract1.reload.payment_term
+      assert_equal @new_payment_term, @contract2.reload.payment_term
+    end
+  end
+end