Throw an error when no cldr provided

Author: bdebinska

lib/value_formatters.ex

@@ -112,8 +112,15 @@ defmodule ValueFormatters do
     end
   end
 
-  # FIXME: Nicer error
-  defp cldr(opts, mod_name), do: Keyword.fetch!(opts, :cldr) |> Module.concat(mod_name)
+  defp cldr(opts, mod_name) do
+    with {:ok, cldr} <- Keyword.fetch(opts, :cldr) do
+      Module.concat(cldr, mod_name)
+    else
+      :error ->
+        raise ArgumentError,
+          message: "The :cldr option is required."
+    end
+  end
 
   defp format_number(value, number_definition, opts) when is_number(value) do
     precision = Map.get(number_definition, "precision")

test/cldr.ex

@@ -1,7 +1,6 @@
 # For test purposes only
 defmodule ValueFormatters.Cldr do
   use Cldr,
-    # Available locales are defined in the config files s.t. they can vary by environment.
     otp_app: :value_formatters,
     default_locale: "en",
     data_dir: "./priv/cldr",

test/value_formatters_test.exs

@@ -621,4 +621,12 @@ defmodule ValueFormattersTest do
              ) == {:ok, "123.0 <span class=\"text-gray-500\">kg</span>"}
     end
   end
+
+  describe "missing cldr" do
+    test "returns error when cldr is not available" do
+      assert_raise ArgumentError, "The :cldr option is required.", fn ->
+        ValueFormatters.to_string(1.234, %{"format" => "number"}, [])
+      end
+    end
+  end
 end