Fix error where to_currency_code/1 would break for countries with no … (

#48)

* Fix error where to_currency_code/1 would break for countries with no currencies

* Return Cldr.UnknownCurrencyError from to_currency_code/1 when no currency exists

lib/cldr/territory.ex

@@ -813,6 +813,9 @@ defmodule Cldr.Territory do
 
       iex> Cldr.Territory.to_currency_code("cu")
       {:ok, :CUP}
+
+      iex> Cldr.Territory.to_currency_code(:CQ)
+      {:error, {Cldr.UnknownCurrencyError, "No currencies for :CQ were found"}}
   """
   @doc since: "1.2.0"
   @spec to_currency_code(atom() | String.t() | LanguageTag.t(), Keyword.t()) :: {:ok, atom() | String.t() | charlist()} | {:error, {module(), String.t()}}
@@ -823,11 +826,11 @@ defmodule Cldr.Territory do
       {:error, reason} -> {:error, reason}
 
       {:ok, [code | _]} -> {:ok, code}
+
+      {:ok, []} -> {:error, {Cldr.UnknownCurrencyError, "No currencies for #{inspect territory_code} were found"}}
     end
   end
 
-
-
   @doc """
   The same as `to_currency_code/2`, but raises an exception if it fails.
 
@@ -862,7 +865,6 @@ defmodule Cldr.Territory do
     end
   end
 
-
   @doc """
   A helper method to get a territory's currency codes.
   Returns `{:ok, list}` if successful, otherwise `{:error, reason}`.

test/territory_test.exs

@@ -545,4 +545,32 @@ defmodule Cldr.TerritoryTest do
                Territory.known_territory_subdivisions(:NOPE, TestBackend.Cldr)
     end
   end
+
+  describe "to_currency_code/1" do
+    test "with valid params" do
+      assert {:ok, :USD} == Territory.to_currency_code(:US)
+      assert {:ok, "DKK"} == Territory.to_currency_code(:DK, as: :binary)
+    end
+
+    test "with invalid params" do
+      assert {:error, {Cldr.UnknownCurrencyError, "No currencies for :CQ were found"}} == Territory.to_currency_code(:CQ)
+      assert {:error, {Cldr.UnknownTerritoryError, "The territory \"zz\" is unknown"}} == Territory.to_currency_code("zz")
+    end
+  end
+
+  describe "to_currency_code!/1" do
+    test "with valid params" do
+      assert :GBP == Cldr.Territory.to_currency_code!(:UK)
+      assert "SEK" == Cldr.Territory.to_currency_code!(:SE, as: :binary)
+    end
+
+    test "with invalid params" do
+      assert_raise Cldr.UnknownCurrencyError, "No currencies for :CQ were found", fn ->
+        Territory.to_currency_code!(:CQ)
+      end
+      assert_raise Cldr.UnknownTerritoryError, "The territory \"zzzzz\" is unknown", fn ->
+        Territory.to_currency_code!("zzzzz")
+      end
+    end
+  end
 end