Merge pull request #1146 from sunny/add-to_nearest_cash_value

Add `Money#to_nearest_cash_value` to return a rounded Money instance to the smallest denomination

Author: yukideluxe

AUTHORS

@@ -1,8 +1,8 @@
 Abhay Kumar
 Adrian Longley
+Alex Speller
 Alexander Donkin
 Alexander Ross
-Alex Speller
 Andreas Loupasakis
 Andrei
 Andrew White
@@ -49,8 +49,8 @@ Greg Byrne
 Hakan Ensari
 Hongli Lai
 Ilia Lobsanov
-Ivan Shamatov
 Ingo Wichmann
+Ivan Shamatov
 Jack Spiva
 Jacob Atzen
 James Cotterill
@@ -83,8 +83,8 @@ Marco Otte-Witte
 Mateus Gomes
 Mateusz Wolsza
 Matias Korhonen
-Matthew McEachen
 Matt Jankowski
+Matthew McEachen
 Max Melentiev
 Michael Irwin
 Michael J. Cohen
@@ -96,14 +96,15 @@ Mike Połétyn
 Musannif Zahir
 Neil Middleton
 Nick Lozon
+Nicolay Hvidsten
 Nihad Abbasov
 Olek Janiszewski
 Orien Madgwick
-Paweł Madejski
 Paul McMahon
 Paulo Diniz
 Pavan Sudarshan
 Pavel Gabriel
+Paweł Madejski
 pconnor
 Pedro Nascimento
 Pelle Braendgaard
@@ -119,9 +120,11 @@ sankaranarayanan
 Scott Pierce
 Semyon Perepelitsa
 Shane Emmons
+Simon Neutert
 Simone Carletti
 Spencer Rinehart
 Steve Morris
+Sunny Ripert
 Thomas E Enebo
 Thomas Weymuth
 Ticean Bennett
@@ -142,5 +145,3 @@ Yuri Sidorov
 Yuusuke Takizawa
 Zubin Henner
 Бродяной Александр
-Nicolay Hvidsten
-Simon Neutert

CHANGELOG.md

@@ -19,7 +19,9 @@
 - Add Zimbabwe Gold (ZWG) currency
 - Update thousands_separator for CHF
 - Add Caribbean Guilder (XCG) as replacement for Netherlands Antillean Gulden (ANG)
-- Add `Currency#cents_based?` to check if currency is cents-based
+- Add `Money#to_nearest_cash_value` to return a rounded Money instance to the smallest denomination
+- Deprecate `Money#round_to_nearest_cash_value` in favor of calling `to_nearest_cash_value.fractional`
+- Add `Money::Currency#cents_based?` to check if currency is cents-based
 - Add ability to nest `Money.with_rounding_mode` blocks
 - Allow `nil` to be used as a default_currency
 - Add ability to nest `Money.with_bank` blocks

CONTRIBUTING.md

@@ -7,8 +7,8 @@
 3. Make sure everything is working: `bundle exec rake spec`
 4. Make your changes
 5. Test your changes
-5. Create a Pull Request
-6. Celebrate!!!!!
+6. Create a Pull Request
+7. Celebrate! 🎉
 
 ## Notes
 

README.md

@@ -471,7 +471,7 @@ Money.from_amount(2.34567).format #=> "$2.34567"
 
 To round to the nearest cent (or anything more precise), you can use the `round` method. However, note that the `round` method on a `Money` object does not work the same way as a normal Ruby `Float` object. Money's `round` method accepts different arguments. The first argument to the round method is the rounding mode, while the second argument is the level of precision relative to the cent.
 
-```
+```ruby
 # Float
 2.34567.round     #=> 2
 2.34567.round(2)  #=> 2.35
@@ -484,10 +484,18 @@ Money.from_cents(2.34567).round(BigDecimal::ROUND_DOWN, 2).format #=> "$0.0234"
 ```
 
 You can set the default rounding mode by passing one of the `BigDecimal` mode enumerables like so:
+
 ```ruby
 Money.rounding_mode = BigDecimal::ROUND_HALF_EVEN
 ```
-See [BigDecimal::ROUND_MODE](https://ruby-doc.org/3.4.1/gems/bigdecimal/BigDecimal.html#ROUND_MODE) for more information
+
+See [BigDecimal::ROUND_MODE](https://ruby-doc.org/3.4.1/gems/bigdecimal/BigDecimal.html#ROUND_MODE) for more information.
+
+To round to the nearest cash value in currencies without small denominations:
+
+```ruby
+Money.from_cents(11_11, "CHF").to_nearest_cash_value.format # => "CHF 11.10"
+```
 
 ## Ruby on Rails
 
@@ -527,7 +535,7 @@ This will work seamlessly with [rails-i18n](https://github.com/svenfuchs/rails-i
 
 If you wish to disable this feature and use defaults instead:
 
-``` ruby
+```ruby
 Money.locale_backend = nil
 ```
 

lib/money/money.rb

@@ -69,15 +69,31 @@ def fractional
   #
   # @see infinite_precision
   def round_to_nearest_cash_value
+    warn "[DEPRECATION] `round_to_nearest_cash_value` is deprecated - use " \
+         "`to_nearest_cash_value.fractional` instead"
+
+    to_nearest_cash_value.fractional
+  end
+
+  # Round a given amount of money to the nearest possible money in cash value.
+  # For example, in Swiss franc (CHF), the smallest possible amount of cash
+  # value is CHF 0.05. Therefore, this method rounds CHF 0.07 to CHF 0.05, and
+  # CHF 0.08 to CHF 0.10.
+  #
+  # @return [Money]
+  def to_nearest_cash_value
     unless self.currency.smallest_denomination
-      raise UndefinedSmallestDenomination, 'Smallest denomination of this currency is not defined'
+      raise UndefinedSmallestDenomination,
+            "Smallest denomination of this currency is not defined"
     end
 
     fractional = as_d(@fractional)
     smallest_denomination = as_d(self.currency.smallest_denomination)
-    rounded_value = (fractional / smallest_denomination).round(0, self.class.rounding_mode) * smallest_denomination
+    rounded_value =
+      (fractional / smallest_denomination)
+        .round(0, self.class.rounding_mode) * smallest_denomination
 
-    return_value(rounded_value)
+    dup_with(fractional: return_value(rounded_value))
   end
 
   # @!attribute [r] currency

sig/lib/money/money.rbs

@@ -58,6 +58,14 @@ class Money
   # @see Money.default_infinite_precision
   def round_to_nearest_cash_value: () -> (Integer | BigDecimal)
 
+  # Round a given amount of money to the nearest possible money in cash value.
+  # For example, in Swiss franc (CHF), the smallest possible amount of cash
+  # value is CHF 0.05. Therefore, this method rounds CHF 0.07 to CHF 0.05, and
+  # CHF 0.08 to CHF 0.10.
+  #
+  # @return [Money]
+  def to_nearest_cash_value: () -> Money
+
   attr_reader currency: Currency
 
   attr_reader bank: untyped

spec/money_spec.rb

@@ -562,6 +562,36 @@ def expectation.fractional
     end
   end
 
+  describe "#to_nearest_cash_value" do
+    it "rounds to the nearest possible cash value" do
+      expect(Money.new(23_50, "AED").to_nearest_cash_value).to eq(Money.new(23_50, "AED"))
+      expect(Money.new(-23_50, "AED").to_nearest_cash_value).to eq(Money.new(-23_50, "AED"))
+      expect(Money.new(22_13, "AED").to_nearest_cash_value).to eq(Money.new(22_25, "AED"))
+      expect(Money.new(-22_13, "AED").to_nearest_cash_value).to eq(Money.new(-22_25, "AED"))
+      expect(Money.new(22_12, "AED").to_nearest_cash_value).to eq(Money.new(22_00, "AED"))
+      expect(Money.new(-22_12, "AED").to_nearest_cash_value).to eq(Money.new(-22_00, "AED"))
+
+      expect(Money.new(1_78, "CHF").to_nearest_cash_value).to eq(Money.new(1_80, "CHF"))
+      expect(Money.new(-1_78, "CHF").to_nearest_cash_value).to eq(Money.new(-1_80, "CHF"))
+      expect(Money.new(1_77, "CHF").to_nearest_cash_value).to eq(Money.new(1_75, "CHF"))
+      expect(Money.new(-1_77, "CHF").to_nearest_cash_value).to eq(Money.new(-1_75, "CHF"))
+      expect(Money.new(1_75, "CHF").to_nearest_cash_value).to eq(Money.new(1_75, "CHF"))
+      expect(Money.new(-1_75, "CHF").to_nearest_cash_value).to eq(Money.new(-1_75, "CHF"))
+
+      expect(Money.new(2_99, "USD").to_nearest_cash_value).to eq(Money.new(2_99, "USD"))
+      expect(Money.new(-2_99, "USD").to_nearest_cash_value).to eq(Money.new(-2_99, "USD"))
+      expect(Money.new(3_00, "USD").to_nearest_cash_value).to eq(Money.new(3_00, "USD"))
+      expect(Money.new(-3_00, "USD").to_nearest_cash_value).to eq(Money.new(-3_00, "USD"))
+      expect(Money.new( 3_01, "USD").to_nearest_cash_value).to eq(Money.new(3_01, "USD"))
+      expect(Money.new(-3_01, "USD").to_nearest_cash_value).to eq(Money.new(-3_01, "USD"))
+    end
+
+    it "raises an error if smallest denomination is not defined" do
+      expect {Money.new(1_00, "XAG").to_nearest_cash_value}
+        .to raise_error(Money::UndefinedSmallestDenomination)
+    end
+  end
+
   describe "#amount" do
     it "returns the amount of cents as dollars" do
       expect(Money.new(1_00).amount).to eq 1