Merge pull request mbulat#15 from willglynn/balance_refactoring

Balance refactoring

app/models/plutus/account.rb

@@ -32,14 +32,36 @@ module Plutus
   class Account < ActiveRecord::Base
     attr_accessible :name, :contra
 
-    has_many :credit_amounts
-    has_many :debit_amounts
+    has_many :credit_amounts, :extend => AmountsExtension
+    has_many :debit_amounts, :extend => AmountsExtension
     has_many :credit_transactions, :through => :credit_amounts, :source => :transaction
     has_many :debit_transactions, :through => :debit_amounts, :source => :transaction
 
     validates_presence_of :type, :name
     validates_uniqueness_of :name
 
+    # The credit balance for the account.
+    #
+    # @example
+    #   >> asset.credits_balance
+    #   => #<BigDecimal:103259bb8,'0.1E4',4(12)>
+    #
+    # @return [BigDecimal] The decimal value credit balance
+    def credits_balance
+      credit_amounts.balance
+    end
+
+    # The debit balance for the account.
+    #
+    # @example
+    #   >> asset.debits_balance
+    #   => #<BigDecimal:103259bb8,'0.3E4',4(12)>
+    #
+    # @return [BigDecimal] The decimal value credit balance
+    def debits_balance
+      debit_amounts.balance
+    end
+
     # The trial balance of all accounts in the system. This should always equal zero,
     # otherwise there is an error in the system.
     #

app/models/plutus/amounts_extension.rb

@@ -0,0 +1,17 @@
+module Plutus
+  # Association extension for has_many :amounts relations. Internal.
+  module AmountsExtension
+    # Returns a sum of the referenced Amount objects.
+    def balance
+      balance = BigDecimal.new('0')
+      each do |amount_record|
+        if amount_record.amount
+          balance += amount_record.amount
+        else
+          balance = nil
+        end
+      end
+      return balance
+    end
+  end
+end

app/models/plutus/asset.rb

@@ -9,36 +9,6 @@ module Plutus
   # @author Michael Bulat
   class Asset < Account
 
-    # The credit balance for the account.
-    #
-    # @example
-    #   >> asset.credits_balance
-    #   => #<BigDecimal:103259bb8,'0.1E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def credits_balance
-      credits_balance = BigDecimal.new('0')
-      credit_amounts.each do |credit_amount|
-        credits_balance += credit_amount.amount
-      end
-      return credits_balance
-    end
-
-    # The debit balance for the account.
-    #
-    # @example
-    #   >> asset.debits_balance
-    #   => #<BigDecimal:103259bb8,'0.3E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def debits_balance
-      debits_balance = BigDecimal.new('0')
-      debit_amounts.each do |debit_amount|
-        debits_balance += debit_amount.amount
-      end
-      return debits_balance
-    end
-
     # The balance of the account.
     #
     # Assets have normal debit balances, so the credits are subtracted from the debits

app/models/plutus/equity.rb

@@ -9,37 +9,6 @@ module Plutus
   # @author Michael Bulat
   class Equity < Account
 
-    # The credit balance for the account.
-    #
-    # @example
-    #   >> equity.credits_balance
-    #   => #<BigDecimal:103259bb8,'0.3E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def credits_balance
-      credits_balance = BigDecimal.new('0')
-      credit_amounts.each do |credit_amount|
-        credits_balance = credits_balance + credit_amount.amount
-      end
-      return credits_balance
-    end
-
-    # The debit balance for the account.
-    #
-    # @example
-    #   >> equity.debits_balance
-    #   => #<BigDecimal:103259bb8,'0.1E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def debits_balance
-      debits_balance = BigDecimal.new('0')
-      debit_amounts.each do |debit_amount|
-        debits_balance = debits_balance + debit_amount.amount
-      end
-      return debits_balance
-    end
-
-
     # The balance of the account.
     #
     # Equity accounts have normal credit balances, so the debits are subtracted from the credits

app/models/plutus/expense.rb

@@ -9,36 +9,6 @@ module Plutus
   # @author Michael Bulat
   class Expense < Account
 
-    # The credit balance for the account.
-    #
-    # @example
-    #   >> expense.credits_balance
-    #   => #<BigDecimal:103259bb8,'0.1E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def credits_balance
-      credits_balance = BigDecimal.new('0')
-      credit_amounts.each do |credit_amount|
-        credits_balance = credits_balance + credit_amount.amount
-      end
-      return credits_balance
-    end
-
-    # The debit balance for the account.
-    #
-    # @example
-    #   >> expense.debits_balance
-    #   => #<BigDecimal:103259bb8,'0.3E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def debits_balance
-      debits_balance = BigDecimal.new('0')
-      debit_amounts.each do |debit_amount|
-        debits_balance = debits_balance + debit_amount.amount
-      end
-      return debits_balance
-    end
-
     # The balance of the account.
     #
     # Expenses have normal debit balances, so the credits are subtracted from the debits

app/models/plutus/liability.rb

@@ -9,36 +9,6 @@ module Plutus
   # @author Michael Bulat
   class Liability < Account
 
-    # The credit balance for the account.
-    #
-    # @example
-    #   >> liability.credits_balance
-    #   => #<BigDecimal:103259bb8,'0.3E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def credits_balance
-      credits_balance = BigDecimal.new('0')
-      credit_amounts.each do |credit_amount|
-        credits_balance = credits_balance + credit_amount.amount
-      end
-      return credits_balance
-    end
-
-    # The debit balance for the account.
-    #
-    # @example
-    #   >> liability.debits_balance
-    #   => #<BigDecimal:103259bb8,'0.1E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def debits_balance
-      debits_balance = BigDecimal.new('0')
-      debit_amounts.each do |debit_amount|
-        debits_balance = debits_balance + debit_amount.amount
-      end
-      return debits_balance
-    end
-
     # The balance of the account.
     #
     # Liability accounts have normal credit balances, so the debits are subtracted from the credits

app/models/plutus/revenue.rb

@@ -9,36 +9,6 @@ module Plutus
   # @author Michael Bulat
   class Revenue < Account
 
-    # The credit balance for the account.
-    #
-    # @example
-    #   >> revenue.credits_balance
-    #   => #<BigDecimal:103259bb8,'0.3E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def credits_balance
-      credits_balance = BigDecimal.new('0')
-      credit_amounts.each do |credit_amount|
-        credits_balance = credits_balance + credit_amount.amount
-      end
-      return credits_balance
-    end
-
-    # The debit balance for the account.
-    #
-    # @example
-    #   >> revenue.debits_balance
-    #   => #<BigDecimal:103259bb8,'0.1E4',4(12)>
-    #
-    # @return [BigDecimal] The decimal value credit balance
-    def debits_balance
-      debits_balance = BigDecimal.new('0')
-      debit_amounts.each do |debit_amount|
-        debits_balance = debits_balance + debit_amount.amount
-      end
-      return debits_balance
-    end
-
     # The balance of the account.
     #
     # Revenue accounts have normal credit balances, so the debits are subtracted from the credits

app/models/plutus/transaction.rb

@@ -25,8 +25,8 @@ class Transaction < ActiveRecord::Base
     attr_accessible :description, :commercial_document
 
     belongs_to :commercial_document, :polymorphic => true
-    has_many :credit_amounts
-    has_many :debit_amounts
+    has_many :credit_amounts, :extend => AmountsExtension
+    has_many :debit_amounts, :extend => AmountsExtension
     has_many :credit_accounts, :through => :credit_amounts, :source => :account
     has_many :debit_accounts, :through => :debit_amounts, :source => :account
 
@@ -71,13 +71,7 @@ def has_debit_amounts?
       end
 
       def amounts_cancel?
-        errors[:base] << "The credit and debit amounts are not equal" if difference_of_amounts != 0
-      end
-
-      def difference_of_amounts
-        credit_amount_total = credit_amounts.inject(0) {|sum, credit_amount| sum + credit_amount.amount.to_i}
-        debit_amount_total = debit_amounts.inject(0) {|sum, debit_amount| sum + debit_amount.amount.to_i}
-        credit_amount_total - debit_amount_total  
+        errors[:base] << "The credit and debit amounts are not equal" if credit_amounts.balance != debit_amounts.balance
       end
   end
 end

spec/models/transaction_spec.rb

@@ -52,6 +52,14 @@ module Plutus
       transaction.errors['base'].should == ["The credit and debit amounts are not equal"]
     end
 
+    it "should require the debit and credit amounts to cancel even with fractions" do
+      transaction = FactoryGirl.build(:transaction)
+      transaction.credit_amounts << FactoryGirl.build(:credit_amount, :amount => 100.1, :transaction => transaction)
+      transaction.debit_amounts << FactoryGirl.build(:debit_amount, :amount => 100.2, :transaction => transaction)
+      transaction.should_not be_valid
+      transaction.errors['base'].should == ["The credit and debit amounts are not equal"]
+    end
+
     it "should have a polymorphic commercial document associations" do
       mock_document = FactoryGirl.create(:asset) # one would never do this, but it allows us to not require a migration for the test
       transaction = FactoryGirl.build(:transaction_with_credit_and_debit, :commercial_document => mock_document)