Fix split/2 to round :down when remainder is negative. Closes #173

lib/money.ex

@@ -1926,36 +1926,52 @@ defmodule Money do
   1. Round the money amount to the required currency precision using
   `Money.round/1`
 
-  2. Divide the result of step 1 by the integer divisor
+  2. Divide the result of step 1 by the integer divisor.
 
   3. Round the result of the division to the precision of the currency
-  using `Money.round/1`
+  using `Money.round/1`. If the deault rounding mode results in a
+  negative remainder, the rounding is done again using rounding mode
+  `:down`.
 
   4. Return two numbers: the result of the division and any remainder
   that could not be applied given the precision of the currency.
 
   ## Examples
 
-      Money.split Money.new(123.5, :JPY), 3
+      Money.split(Money.new(123.5, :JPY), 3)
       {¥41, ¥1}
 
-      Money.split Money.new(123.4, :JPY), 3
+      Money.split(Money.new(123.4, :JPY), 3)
       {¥41, ¥0}
 
-      Money.split Money.new(123.7, :USD), 9
+      Money.split(Money.new(123.7, :USD), 9)
       {$13.74, $0.04}
 
+      iex> Money.split(Money.new( :USD, 200), 3)
+      {Money.new(:USD, "66.66"), Money.new(:USD, "0.02")}
+
   """
   @spec split(Money.t(), non_neg_integer) :: {Money.t(), Money.t()}
   def split(%Money{} = money, parts) when is_integer(parts) do
     rounded_money = Money.round(money)
 
+    {split, remainder} = split_with_rounding(money, rounded_money, parts, default_rounding_mode())
+
+    if compare(remainder, zero(money)) == :lt do
+      split_with_rounding(money, rounded_money, parts, :down)
+    else
+      {split, remainder}
+    end
+  end
+
+  defp split_with_rounding(money, rounded_money, parts, rounding_mode) do
     div =
       rounded_money
       |> Money.div!(parts)
-      |> round
+      |> round(rounding_mode: rounding_mode)
 
     remainder = sub!(money, mult!(div, parts))
+
     {div, remainder}
   end
 
@@ -2949,6 +2965,15 @@ defmodule Money do
     @app_name
   end
 
+  @doc """
+  Returns the default rounding mode.
+
+  """
+  @doc since: "5.18.1"
+  def default_rounding_mode do
+    @default_rounding_mode
+  end
+
   @doc """
   Returns the default `ex_cldr` backend configured
   for `Money`, if any. If no default backing is

mix.exs

@@ -1,7 +1,7 @@
 defmodule Money.Mixfile do
   use Mix.Project
 
-  @version "5.18.0"
+  @version "5.18.1"
 
   def project do
     [

mix.lock

@@ -5,17 +5,17 @@
   "combine": {:hex, :combine, "0.10.0", "eff8224eeb56498a2af13011d142c5e7997a80c8f5b97c499f84c841032e429f", [:mix], [], "hexpm", "1b1dbc1790073076580d0d1d64e42eae2366583e7aecd455d1215b0d16f2451b"},
   "decimal": {:hex, :decimal, "2.1.1", "5611dca5d4b2c3dd497dec8f68751f1f1a54755e8ed2a966c2633cf885973ad6", [:mix], [], "hexpm", "53cfe5f497ed0e7771ae1a475575603d77425099ba5faef9394932b35020ffcc"},
   "deep_merge": {:hex, :deep_merge, "1.0.0", "b4aa1a0d1acac393bdf38b2291af38cb1d4a52806cf7a4906f718e1feb5ee961", [:mix], [], "hexpm", "ce708e5f094b9cd4e8f2be4f00d2f4250c4095be93f8cd6d018c753894885430"},
-  "dialyxir": {:hex, :dialyxir, "1.4.3", "edd0124f358f0b9e95bfe53a9fcf806d615d8f838e2202a9f430d59566b6b53b", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "bf2cfb75cd5c5006bec30141b131663299c661a864ec7fbbc72dfa557487a986"},
+  "dialyxir": {:hex, :dialyxir, "1.4.4", "fb3ce8741edeaea59c9ae84d5cec75da00fa89fe401c72d6e047d11a61f65f70", [:mix], [{:erlex, ">= 0.2.7", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "cd6111e8017ccd563e65621a4d9a4a1c5cd333df30cebc7face8029cacb4eff6"},
   "digital_token": {:hex, :digital_token, "1.0.0", "454a4444061943f7349a51ef74b7fb1ebd19e6a94f43ef711f7dae88c09347df", [:mix], [{:cldr_utils, "~> 2.17", [hex: :cldr_utils, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "8ed6f5a8c2fa7b07147b9963db506a1b4c7475d9afca6492136535b064c9e9e6"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.41", "ab34711c9dc6212dda44fcd20ecb87ac3f3fce6f0ca2f28d4a00e4154f8cd599", [:mix], [], "hexpm", "a81a04c7e34b6617c2792e291b5a2e57ab316365c2644ddc553bb9ed863ebefa"},
   "elixir_xml_to_map": {:hex, :elixir_xml_to_map, "3.1.0", "4d6260486a8cce59e4bf3575fe2dd2a24766546ceeef9f93fcec6f7c62a2827a", [:mix], [{:erlsom, "~> 1.4", [hex: :erlsom, repo: "hexpm", optional: false]}], "hexpm", "8fe5f2e75f90bab07ee2161120c2dc038ebcae8135554f5582990f1c8c21f911"},
   "erlex": {:hex, :erlex, "0.2.7", "810e8725f96ab74d17aac676e748627a07bc87eb950d2b83acd29dc047a30595", [:mix], [], "hexpm", "3ed95f79d1a844c3f6bf0cea61e0d5612a42ce56da9c03f01df538685365efb0"},
   "erlsom": {:hex, :erlsom, "1.5.1", "c8fe2babd33ff0846403f6522328b8ab676f896b793634cfe7ef181c05316c03", [:rebar3], [], "hexpm", "7965485494c5844dd127656ac40f141aadfa174839ec1be1074e7edf5b4239eb"},
   "ex_cldr": {:hex, :ex_cldr, "2.40.1", "c1fcb0cd9d2a70d28f4540a99f32127e7f1813e0db109d65ab29dea5337ae266", [:mix], [{:cldr_utils, "~> 2.28", [hex: :cldr_utils, repo: "hexpm", optional: false]}, {:decimal, "~> 1.6 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:gettext, "~> 0.19", [hex: :gettext, repo: "hexpm", optional: true]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:nimble_parsec, "~> 0.5 or ~> 1.0", [hex: :nimble_parsec, repo: "hexpm", optional: true]}], "hexpm", "509810702e8e81991851d9426ffe6b34b48b7b9baa12922e7b3fb8f6368606f3"},
-  "ex_cldr_currencies": {:hex, :ex_cldr_currencies, "2.16.2", "670d96cc4fb18cfebd82488ed687742683be2d0725d66ec051578d4b13539aa8", [:mix], [{:ex_cldr, "~> 2.38", [hex: :ex_cldr, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "2ccfac2838f4df8c8e5424dbc68eb2f3ac9eeb45e10365050901f7ac7a914ce1"},
+  "ex_cldr_currencies": {:hex, :ex_cldr_currencies, "2.16.3", "1ec6444b5d0c0aabba5a3bc321d73f1c9c751c6add92e7fb7775ccc071d96bd8", [:mix], [{:ex_cldr, "~> 2.38", [hex: :ex_cldr, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "4d1b5f8449fdf0ece6a2e5c7401ad8fcfde77ee6ea480bddc16e266dfa2b570c"},
   "ex_cldr_numbers": {:hex, :ex_cldr_numbers, "2.33.3", "9fedcf279a17d19abdf8872738472326e82378d90ec2dd9756a0c84558c86b36", [:mix], [{:decimal, "~> 1.6 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:digital_token, "~> 0.3 or ~> 1.0", [hex: :digital_token, repo: "hexpm", optional: false]}, {:ex_cldr, "~> 2.38", [hex: :ex_cldr, repo: "hexpm", optional: false]}, {:ex_cldr_currencies, "~> 2.16", [hex: :ex_cldr_currencies, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "4a0d90d06710c1499528d5f536c539379a73a68d4679c55375198a798d138442"},
   "ex_doc": {:hex, :ex_doc, "0.34.2", "13eedf3844ccdce25cfd837b99bea9ad92c4e511233199440488d217c92571e8", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "5ce5f16b41208a50106afed3de6a2ed34f4acfd65715b82a0b84b49d995f95c1"},
-  "expo": {:hex, :expo, "1.0.1", "f9e2f984f5b8d195815d52d0ba264798c12c8d2f2606f76fa4c60e8ebe39474d", [:mix], [], "hexpm", "f250b33274e3e56513644858c116f255d35c767c2b8e96a512fe7839ef9306a1"},
+  "expo": {:hex, :expo, "1.1.0", "f7b9ed7fb5745ebe1eeedf3d6f29226c5dd52897ac67c0f8af62a07e661e5c75", [:mix], [], "hexpm", "fbadf93f4700fb44c331362177bdca9eeb8097e8b0ef525c9cc501cb9917c960"},
   "exprintf": {:hex, :exprintf, "0.2.1", "b7e895dfb00520cfb7fc1671303b63b37dc3897c59be7cbf1ae62f766a8a0314", [:mix], [], "hexpm", "20a0e8c880be90e56a77fcc82533c5d60c643915c7ce0cc8aa1e06ed6001da28"},
   "exprof": {:hex, :exprof, "0.2.4", "13ddc0575a6d24b52e7c6809d2a46e9ad63a4dd179628698cdbb6c1f6e497c98", [:mix], [{:exprintf, "~> 0.2", [hex: :exprintf, repo: "hexpm", optional: false]}], "hexpm", "0884bcb66afc421c75d749156acbb99034cc7db6d3b116c32e36f32551106957"},
   "gettext": {:hex, :gettext, "0.26.1", "38e14ea5dcf962d1fc9f361b63ea07c0ce715a8ef1f9e82d3dfb8e67e0416715", [:mix], [{:expo, "~> 0.5.1 or ~> 1.0", [hex: :expo, repo: "hexpm", optional: false]}], "hexpm", "01ce56f188b9dc28780a52783d6529ad2bc7124f9744e571e1ee4ea88bf08734"},
@@ -35,9 +35,9 @@
   "poison": {:hex, :poison, "6.0.0", "9bbe86722355e36ffb62c51a552719534257ba53f3271dacd20fbbd6621a583a", [:mix], [{:decimal, "~> 2.1", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "bb9064632b94775a3964642d6a78281c07b7be1319e0016e1643790704e739a2"},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.7", "354c321cf377240c7b8716899e182ce4890c5938111a1296add3ec74cf1715df", [:make, :mix, :rebar3], [], "hexpm", "fe4c190e8f37401d30167c8c405eda19469f34577987c76dde613e838bbc67f8"},
   "statistex": {:hex, :statistex, "1.0.0", "f3dc93f3c0c6c92e5f291704cf62b99b553253d7969e9a5fa713e5481cd858a5", [:mix], [], "hexpm", "ff9d8bee7035028ab4742ff52fc80a2aa35cece833cf5319009b52f1b5a86c27"},
-  "stream_data": {:hex, :stream_data, "1.1.1", "fd515ca95619cca83ba08b20f5e814aaf1e5ebff114659dc9731f966c9226246", [:mix], [], "hexpm", "45d0cd46bd06738463fd53f22b70042dbb58c384bb99ef4e7576e7bb7d3b8c8c"},
+  "stream_data": {:hex, :stream_data, "1.1.2", "05499eaec0443349ff877aaabc6e194e82bda6799b9ce6aaa1aadac15a9fdb4d", [:mix], [], "hexpm", "129558d2c77cbc1eb2f4747acbbea79e181a5da51108457000020a906813a1a9"},
   "timex": {:hex, :timex, "3.7.11", "bb95cb4eb1d06e27346325de506bcc6c30f9c6dea40d1ebe390b262fad1862d1", [:mix], [{:combine, "~> 0.10", [hex: :combine, repo: "hexpm", optional: false]}, {:gettext, "~> 0.20", [hex: :gettext, repo: "hexpm", optional: false]}, {:tzdata, "~> 1.1", [hex: :tzdata, repo: "hexpm", optional: false]}], "hexpm", "8b9024f7efbabaf9bd7aa04f65cf8dcd7c9818ca5737677c7b76acbc6a94d1aa"},
-  "tzdata": {:hex, :tzdata, "1.1.1", "20c8043476dfda8504952d00adac41c6eda23912278add38edc140ae0c5bcc46", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "a69cec8352eafcd2e198dea28a34113b60fdc6cb57eb5ad65c10292a6ba89787"},
+  "tzdata": {:hex, :tzdata, "1.1.2", "45e5f1fcf8729525ec27c65e163be5b3d247ab1702581a94674e008413eef50b", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "cec7b286e608371602318c414f344941d5eb0375e14cfdab605cca2fe66cba8b"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.7.0", "bc84380c9ab48177092f43ac89e4dfa2c6d62b40b8bd132b1059ecc7232f9a78", [:rebar3], [], "hexpm", "25eee6d67df61960cf6a794239566599b09e17e668d3700247bc498638152521"},
   "xml_builder": {:hex, :xml_builder, "2.3.0", "69d214c6ad41ae1300b36acff4367551cdfd9dc1b860affc16e103c6b1589053", [:mix], [], "hexpm", "972ec33346a225cd5acd14ab23d4e79042bd37cb904e07e24cd06992dde1a0ed"},
 }