Add tests for register expansion methods with key = []

actionpack/test/template/asset_tag_helper_test.rb

@@ -302,11 +302,16 @@ def test_registering_javascript_expansions_merges_with_existing_expansions
     assert_dom_equal  %(<script src="/javascripts/bank.js" type="text/javascript"></script>\n<script src="/javascripts/robber.js" type="text/javascript"></script>), javascript_include_tag(:can_merge)
   end
 
-  def test_custom_javascript_expansions_with_undefined_symbol
+  def test_custom_javascript_expansions_with_nil_value
     ActionView::Helpers::AssetTagHelper::register_javascript_expansion :monkey => nil
     assert_raise(ArgumentError) { javascript_include_tag('first', :monkey, 'last') }
   end
 
+  def test_custom_javascript_expansions_with_empty_array_value
+    ActionView::Helpers::AssetTagHelper::register_javascript_expansion :monkey => []
+    assert_dom_equal  %(<script src="/javascripts/first.js" type="text/javascript"></script>\n<script src="/javascripts/last.js" type="text/javascript"></script>), javascript_include_tag('first', :monkey, 'last')
+  end
+
   def test_custom_javascript_and_stylesheet_expansion_with_same_name
     ENV["RAILS_ASSET_ID"] = ""
     ActionView::Helpers::AssetTagHelper::register_javascript_expansion :robbery => ["bank", "robber"]
@@ -379,11 +384,16 @@ def test_single_stylesheet_asset_keys_should_take_precedence_over_expansions
     assert_dom_equal  %(<link href="/stylesheets/london.css" media="screen" rel="stylesheet" type="text/css" />\n<link href="/stylesheets/wellington.css" media="screen" rel="stylesheet" type="text/css" />\n<link href="/stylesheets/amsterdam.css" media="screen" rel="stylesheet" type="text/css" />), stylesheet_link_tag('london', :cities)
   end
 
-  def test_custom_stylesheet_expansions_with_undefined_symbol
+  def test_custom_stylesheet_expansions_with_nil_value
     ActionView::Helpers::AssetTagHelper::register_stylesheet_expansion :monkey => nil
     assert_raise(ArgumentError) { stylesheet_link_tag('first', :monkey, 'last') }
   end
 
+  def test_custom_stylesheet_expansions_with_empty_array_value
+    ActionView::Helpers::AssetTagHelper::register_stylesheet_expansion :monkey => []
+    assert_dom_equal  %(<link href="/stylesheets/first.css" rel="stylesheet" type="text/css" media="screen" />\n<link href="/stylesheets/last.css" rel="stylesheet" type="text/css" media="screen" />), stylesheet_link_tag('first', :monkey, 'last')
+  end
+
   def test_registering_stylesheet_expansions_merges_with_existing_expansions
     ENV["RAILS_ASSET_ID"] = ""
     ActionView::Helpers::AssetTagHelper::register_stylesheet_expansion :can_merge => ['bank']