Filter by names (#19)

* filter_by/2 can now be used to search in list attributes like :names

* add alternative name for GB

lib/countries.ex

@@ -15,13 +15,25 @@ defmodule Countries do
   ## Examples
     iex> Countries.filter_by(:region, "Europe")
     [%Countries.Country{address_format: nil, alpha2: "VA" ...
+
+    iex> Countries.filter_by(:names, "Reino Unido")
+    [%Countries.Country{address_format: nil, alpha2: "GB" ...
   """
   def filter_by(attribute, value) do
     Enum.filter(countries(), fn(country) ->
-      Map.get(country, attribute) == value
+      Map.get(country, attribute)
+      |> equals_or_contains_in_list(value)
     end)
   end
 
+  defp equals_or_contains_in_list(attribute, value) when is_list(attribute) do
+    Enum.member?(attribute, value)
+  end
+
+  defp equals_or_contains_in_list(attribute, value) do
+    attribute == value
+  end
+
   @doc """
   Checks if country for specific attribute and value exists.
 

lib/data/countries/GB.yaml

@@ -19,6 +19,7 @@ longitude: 2 00 W
 name: United Kingdom
 names:
 - United Kingdom
+- The United Kingdom
 - Vereinigtes Königreich
 - Royaume-Uni
 - Reino Unido

test/countries_test.exs

@@ -6,6 +6,19 @@ defmodule CountriesTest do
     assert Enum.count(country) == 1
   end
 
+  test "filter countries by name" do
+    countries = Countries.filter_by(:name, "United Kingdom")
+    assert Enum.count(countries) == 1
+  end
+
+  test "filter countries by alternative names" do
+    countries = Countries.filter_by(:names, "Reino Unido")
+    assert Enum.count(countries) == 1
+
+    countries = Countries.filter_by(:names, "The United Kingdom")
+    assert Enum.count(countries) == 1
+  end
+
   test "filter many countries by region" do
     countries = Countries.filter_by(:region, "Europe")
     assert Enum.count(countries) == 51