refactroing wallet service, credit/debit in transaction of db, if have an error we rollback all

app/models/wallet_transaction.rb

@@ -7,4 +7,5 @@ class WalletTransaction < ActiveRecord::Base
   belongs_to :transactable, polymorphic: true
 
   validates_inclusion_of :transaction_type, in: %w( credit debit )
+  validates :user, :wallet, presence: true
 end

app/services/wallet_service.rb

@@ -4,25 +4,36 @@ class WalletService
     @wallet = wallet
   end
 
+  ## credit an amount to wallet, if credit success then return a wallet transaction and notify to admin
   def credit(amount)
-    if @wallet.credit(amount)
-      transaction = WalletTransaction.create(user: @user, wallet: @wallet, transaction_type: 'credit', amount: amount)
-
-      NotificationCenter.call type: 'notify_user_wallet_is_credited',
-                              receiver: @wallet.user,
-                              attached_object: transaction
-      NotificationCenter.call type: 'notify_admin_user_wallet_is_credited',
-                              receiver: User.admins,
-                              attached_object: transaction
-      return true
+    ActiveRecord::Base.transaction do
+      if @wallet.credit(amount)
+        transaction = WalletTransaction.new(user: @user, wallet: @wallet, transaction_type: 'credit', amount: amount)
+        if transaction.save
+          NotificationCenter.call type: 'notify_user_wallet_is_credited',
+                                  receiver: @wallet.user,
+                                  attached_object: transaction
+          NotificationCenter.call type: 'notify_admin_user_wallet_is_credited',
+                                  receiver: User.admins,
+                                  attached_object: transaction
+          return transaction
+        end
+      end
+      raise ActiveRecord::Rollback
     end
     return false
   end
 
+  ## debit an amount to wallet, if debit success then return a wallet transaction
   def debit(amount, transactable)
-    if @wallet.debit(amount)
-      WalletTransaction.create(user: @user, wallet: @wallet, transaction_type: 'debit', amount: amount, transactable: transactable)
-      return true
+    ActiveRecord::Base.transaction do
+      if @wallet.debit(amount)
+        transaction = WalletTransaction.new(user: @user, wallet: @wallet, transaction_type: 'debit', amount: amount, transactable: transactable)
+        if transaction.save
+          return transaction
+        end
+      end
+      raise ActiveRecord::Rollback
     end
     return false
   end

test/models/wallet_transaction_test.rb

@@ -2,7 +2,9 @@ require 'test_helper'
 
 class WalletTransactionTest < ActiveSupport::TestCase
   test 'transaction type must be credit or debit' do
-    transaction = WalletTransaction.new amount: 5
+    @jdupond = User.find_by(username: 'jdupond')
+    @jdupond_wallet = @jdupond.wallet
+    transaction = WalletTransaction.new amount: 5, user: @jdupond, wallet: @jdupond_wallet
     transaction.transaction_type = 'credit'
     assert transaction.valid?
     transaction.transaction_type = 'debit'

test/services/wallet_service_test.rb

@@ -18,22 +18,45 @@ class WalletServiceTest < ActiveSupport::TestCase
 
   test 'create a credit transaction after credit amount to wallet' do
     service = WalletService.new(user: @admin, wallet: @jdupond_wallet)
+    expected_amount = @jdupond_wallet.amount + 10
     assert_equal 0, @jdupond_wallet.wallet_transactions.count
-    assert service.credit(10)
-    transaction = @jdupond_wallet.wallet_transactions.first
+    transaction = service.credit(10)
+    @jdupond_wallet.reload
+    assert transaction
+    assert_equal @jdupond_wallet.amount, expected_amount
     assert_equal transaction.transaction_type, 'credit'
     assert_equal transaction.amount, 10
     assert_equal transaction.user, @admin
     assert_equal transaction.wallet, @jdupond_wallet
   end
 
-  test 'create a debit transaction after debit amoutn to wallet' do
+  test 'create a debit transaction after debit amount to wallet' do
     service = WalletService.new(user: @vlonchamp, wallet: @vlonchamp_wallet)
-    assert service.debit(5, nil)
-    transaction = @vlonchamp_wallet.wallet_transactions.last
+    expected_amount = @vlonchamp_wallet.amount - 5
+    transaction = service.debit(5, nil)
+    @vlonchamp_wallet.reload
+    assert transaction
+    assert_equal @vlonchamp_wallet.amount, expected_amount
     assert_equal transaction.transaction_type, 'debit'
     assert_equal transaction.amount, 5
     assert_equal transaction.user, @vlonchamp
     assert_equal transaction.wallet, @vlonchamp_wallet
   end
+
+  test 'dont debit amount > wallet amount' do
+    service = WalletService.new(user: @vlonchamp, wallet: @vlonchamp_wallet)
+    expected_amount = @vlonchamp_wallet.amount
+    service.debit(100, nil)
+    @vlonchamp_wallet.reload
+    assert_equal @vlonchamp_wallet.amount, expected_amount
+  end
+
+  test 'rollback debited amount if has an error when create wallet transaction' do
+    service = WalletService.new(wallet: @vlonchamp_wallet)
+    expected_amount = @vlonchamp_wallet.amount
+    transaction = service.debit(5, nil)
+    @vlonchamp_wallet.reload
+    assert_equal @vlonchamp_wallet.amount, expected_amount
+    assert_not transaction
+  end
 end