Partial template name does no more have to be a valid Ruby identifier

because the partial renderer would not create an lvar per each template since c67005f221

actionview/CHANGELOG.md

@@ -1,3 +1,13 @@
+*   Partial template name does no more have to be a valid Ruby identifier.
+
+    There used to be a naming rule that the partial name should start with
+    underscore, and should be followed by any combination of letters, numbers
+    and underscores.
+    But now we can give our partials any name starting with underscore, such as
+    _🍔.html.erb.
+
+    *Akira Matsuda*
+
 *   Change the default template handler from `ERB` to `Raw`.
 
     Files without a template handler in their extension will be rendered using the raw

actionview/lib/action_view/renderer/partial_renderer.rb

@@ -519,7 +519,7 @@ module ActionView
     def retrieve_variable(path, as)
       variable = as || begin
         base = path[-1] == "/" ? "" : File.basename(path)
-        raise_invalid_identifier(path) unless base =~ /\A_?([a-z]\w*)(\.\w+)*\z/
+        raise_invalid_identifier(path) unless base =~ /\A_?(.*)(?:\.\w+)*\z/
         $1.to_sym
       end
       if @collection
@@ -530,8 +530,7 @@ module ActionView
     end
 
     IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " +
-                               "make sure your partial name starts with underscore, " +
-                               "and is followed by any combination of letters, numbers and underscores."
+                               "make sure your partial name starts with underscore."
 
     OPTION_AS_ERROR_MESSAGE  = "The value (%s) of the option `as` is not a valid Ruby identifier; " +
                                "make sure it starts with lowercase letter, " +

actionview/test/fixtures/test/_FooBar.html.erb

@@ -0,0 +1 @@
+🍣

actionview/test/template/render_test.rb

@@ -171,18 +171,12 @@ module RenderTestCases
     assert_equal "only partial", @view.render("test/partial_only", :counter_counter => 5)
   end
 
-  def test_render_partial_with_invalid_name
-    e = assert_raises(ArgumentError) { @view.render(:partial => "test/200") }
-    assert_equal "The partial name (test/200) is not a valid Ruby identifier; " +
-      "make sure your partial name starts with underscore, " +
-      "and is followed by any combination of letters, numbers and underscores.", e.message
+  def test_render_partial_with_number
+    assert_nothing_raised { @view.render(:partial => "test/200") }
   end
 
   def test_render_partial_with_missing_filename
-    e = assert_raises(ArgumentError) { @view.render(:partial => "test/") }
-    assert_equal "The partial name (test/) is not a valid Ruby identifier; " +
-      "make sure your partial name starts with underscore, " +
-      "and is followed by any combination of letters, numbers and underscores.", e.message
+    assert_raises(ActionView::MissingTemplate) { @view.render(:partial => "test/") }
   end
 
   def test_render_partial_with_incompatible_object
@@ -190,11 +184,12 @@ module RenderTestCases
     assert_equal "'#{nil.inspect}' is not an ActiveModel-compatible object. It must implement :to_partial_path.", e.message
   end
 
+  def test_render_partial_starting_with_a_capital
+    assert_nothing_raised { @view.render(:partial => 'test/FooBar') }
+  end
+
   def test_render_partial_with_hyphen
-    e = assert_raises(ArgumentError) { @view.render(:partial => "test/a-in") }
-    assert_equal "The partial name (test/a-in) is not a valid Ruby identifier; " +
-      "make sure your partial name starts with underscore, " +
-      "and is followed by any combination of letters, numbers and underscores.", e.message
+    assert_nothing_raised { @view.render(:partial => "test/a-in") }
   end
 
   def test_render_partial_with_invalid_option_as