Multi-currency support: Money + Currency class improvements (#553)

* Money improvements

* Replace all old money usage

test/lib/money_test.rb

@@ -0,0 +1,90 @@
+require "test_helper"
+
+class MoneyTest < ActiveSupport::TestCase
+    test "can create with default currency" do
+        value = Money.new(1000)
+        assert_equal 1000, value.amount
+    end
+
+    test "can create with custom currency" do
+        value1 = Money.new(1000, :EUR)
+        value2 = Money.new(1000, :eur)
+        value3 = Money.new(1000, "eur")
+        value4 = Money.new(1000, "EUR")
+
+        assert_equal value1.currency.iso_code, value2.currency.iso_code
+        assert_equal value2.currency.iso_code, value3.currency.iso_code
+        assert_equal value3.currency.iso_code, value4.currency.iso_code
+    end
+
+    test "equality tests amount and currency" do
+        assert_equal Money.new(1000), Money.new(1000)
+        assert_not_equal Money.new(1000), Money.new(1001)
+        assert_not_equal Money.new(1000, :usd), Money.new(1000, :eur)
+    end
+
+    test "can compare with zero Numeric" do
+        assert_equal Money.new(0), 0
+        assert_raises(TypeError) { Money.new(1) == 1 }
+    end
+
+    test "can negate" do
+        assert_equal (-Money.new(1000)), Money.new(-1000)
+    end
+
+    test "can use comparison operators" do
+        assert_operator Money.new(1000), :>, Money.new(999)
+        assert_operator Money.new(1000), :>=, Money.new(1000)
+        assert_operator Money.new(1000), :<, Money.new(1001)
+        assert_operator Money.new(1000), :<=, Money.new(1000)
+    end
+
+    test "can add and subtract" do
+        assert_equal Money.new(1000) + Money.new(1000), Money.new(2000)
+        assert_equal Money.new(1000) + 1000, Money.new(2000)
+        assert_equal Money.new(1000) - Money.new(1000), Money.new(0)
+        assert_equal Money.new(1000) - 1000, Money.new(0)
+    end
+
+    test "can multiply" do
+        assert_equal Money.new(1000) * 2, Money.new(2000)
+        assert_raises(TypeError) { Money.new(1000) * Money.new(2) }
+    end
+
+    test "can divide" do
+        assert_equal Money.new(1000) / 2, Money.new(500)
+        assert_equal Money.new(1000) / Money.new(500), 2
+        assert_raise(TypeError) { 1000 / Money.new(2) }
+    end
+
+    test "operator order does not matter" do
+        assert_equal Money.new(1000) + 1000, 1000 + Money.new(1000)
+        assert_equal Money.new(1000) - 1000, 1000 - Money.new(1000)
+        assert_equal Money.new(1000) * 2, 2 * Money.new(1000)
+    end
+
+    test "can get absolute value" do
+        assert_equal Money.new(1000).abs, Money.new(1000)
+        assert_equal Money.new(-1000).abs, Money.new(1000)
+    end
+
+    test "can test if zero" do
+        assert Money.new(0).zero?
+        assert_not Money.new(1000).zero?
+    end
+
+    test "can test if negative" do
+        assert Money.new(-1000).negative?
+        assert_not Money.new(1000).negative?
+    end
+
+    test "can test if positive" do
+        assert Money.new(1000).positive?
+        assert_not Money.new(-1000).positive?
+    end
+
+    test "can cast to string with basic formatting" do
+        assert_equal "$1,000.90", Money.new(1000.899).format
+        assert_equal "€1.000,12", Money.new(1000.12, :eur).format
+    end
+end