added pluralized_array method to Hash and tests

lib/jekyll/core_ext.rb

@@ -19,6 +19,28 @@ class Hash
 
     target
   end
+
+  # Read array from the supplied hash favouring the singular key
+  # and then the plural key, and handling any nil entries.
+  #   +hash+ the hash to read from
+  #   +singular_key+ the singular key
+  #   +plural_key+ the singular key
+  #
+  # Returns an array
+  def pluralized_array(singular_key, plural_key)
+    hash = self
+    if hash.has_key?(singular_key)
+      array = [hash[singular_key]] if hash[singular_key]
+    elsif hash.has_key?(plural_key)
+      case hash[plural_key]
+      when String
+        array = hash[plural_key].split
+      when Array
+        array = hash[plural_key].compact
+      end
+    end
+    array || []
+  end
 end
 
 # Thanks, ActiveSupport!

test/test_core_ext.rb

@@ -0,0 +1,66 @@
+require File.dirname(__FILE__) + '/helper'
+
+class TestCoreExt < Test::Unit::TestCase
+  context "hash" do
+
+    context "pluralized_array" do
+
+      should "return empty array with no values" do
+        data = {}
+        assert_equal [], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return empty array with no matching values" do
+        data = { 'foo' => 'bar' }
+        assert_equal [], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return empty array with matching nil singular" do
+        data = { 'foo' => 'bar', 'tag' => nil, 'tags' => ['dog', 'cat'] }
+        assert_equal [], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return single value array with matching singular" do
+        data = { 'foo' => 'bar', 'tag' => 'dog', 'tags' => ['dog', 'cat'] }
+        assert_equal ['dog'], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return single value array with matching singular with spaces" do
+        data = { 'foo' => 'bar', 'tag' => 'dog cat', 'tags' => ['dog', 'cat'] }
+        assert_equal ['dog cat'], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return empty array with matching nil plural" do
+        data = { 'foo' => 'bar', 'tags' => nil }
+        assert_equal [], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return empty array with matching empty array" do
+        data = { 'foo' => 'bar', 'tags' => [] }
+        assert_equal [], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return single value array with matching plural with single string value" do
+        data = { 'foo' => 'bar', 'tags' => 'dog' }
+        assert_equal ['dog'], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return multiple value array with matching plural with single string value with spaces" do
+        data = { 'foo' => 'bar', 'tags' => 'dog cat' }
+        assert_equal ['dog', 'cat'], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return single value array with matching plural with single value array" do
+        data = { 'foo' => 'bar', 'tags' => ['dog'] }
+        assert_equal ['dog'], data.pluralized_array('tag', 'tags')
+      end
+
+      should "return multiple value array with matching plural with multiple value array" do
+        data = { 'foo' => 'bar', 'tags' => ['dog', 'cat'] }
+        assert_equal ['dog', 'cat'], data.pluralized_array('tag', 'tags')
+      end
+
+    end
+
+  end
+end