From cac9e16c1704d4661fd3a8d4bafc9f1247b90886 Mon Sep 17 00:00:00 2001
From: Peng DU <peng@sleede.com>
Date: Tue, 5 Jul 2016 10:38:39 +0200
Subject: [PATCH] cant debit/credit a negative

---
 app/models/wallet.rb       | 14 ++++++++++----
 test/models/wallet_test.rb | 11 +++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/app/models/wallet.rb b/app/models/wallet.rb
index 8c2374e64..17483c6b4 100644
--- a/app/models/wallet.rb
+++ b/app/models/wallet.rb
@@ -5,12 +5,18 @@ class Wallet < ActiveRecord::Base
   validates_numericality_of :amount, greater_than_or_equal_to: 0
 
   def credit(amount)
-    self.amount += amount
-    save
+    if amount.is_a?(Numeric) and amount >= 0
+      self.amount += amount
+      return save
+    end
+    false
   end
 
   def debit(amount)
-    self.amount -= amount
-    save
+    if amount.is_a?(Numeric) and amount >= 0
+      self.amount -= amount
+      return save
+    end
+    false
   end
 end
diff --git a/test/models/wallet_test.rb b/test/models/wallet_test.rb
index ef4d6b52b..c557d58a7 100644
--- a/test/models/wallet_test.rb
+++ b/test/models/wallet_test.rb
@@ -25,4 +25,15 @@ class WalletTest < ActiveSupport::TestCase
     assert w.debit(5)
     assert_equal w.amount, expected_amount
   end
+
+  test 'cant debit/credit a negative' do
+    w = Wallet.new
+    assert_not w.credit(-5)
+    assert_not w.debit(-5)
+  end
+
+  test 'wallet amount cant < 0 after debit' do
+    w = Wallet.new
+    assert_not w.debit(5)
+  end
 end