Deprecate `with_fallbacks` using a block

This patch changes `with_fallbacks` to be a factory method that returns
a new instance of a lookup context which contains the fallback view
paths in addition to the controller specific view paths.  Since the
lookup context is more "read only", we may be able to cache them

1 files changed, 19 insertions, 6 deletions

diff --git a/actionview/test/template/lookup_context_test.rb b/actionview/test/template/lookup_context_test.rb
index 0894925c9f..290f832794 100644
--- a/actionview/test/template/lookup_context_test.rb
+++ b/actionview/test/template/lookup_context_test.rb
@@ -122,19 +122,32 @@ class LookupContextTest < ActiveSupport::TestCase
   test "adds fallbacks to view paths when required" do
     assert_equal 1, @lookup_context.view_paths.size
 
-    @lookup_context.with_fallbacks do
-      assert_equal 3, @lookup_context.view_paths.size
-      assert_includes @lookup_context.view_paths, ActionView::FallbackFileSystemResolver.new("")
-      assert_includes @lookup_context.view_paths, ActionView::FallbackFileSystemResolver.new("/")
+    assert_deprecated do
+      @lookup_context.with_fallbacks do
+        assert_equal 3, @lookup_context.view_paths.size
+        assert_includes @lookup_context.view_paths, ActionView::FallbackFileSystemResolver.new("")
+        assert_includes @lookup_context.view_paths, ActionView::FallbackFileSystemResolver.new("/")
+      end
     end
+
+    @lookup_context = @lookup_context.with_fallbacks
+
+    assert_equal 3, @lookup_context.view_paths.size
+    assert_includes @lookup_context.view_paths, ActionView::FallbackFileSystemResolver.new("")
+    assert_includes @lookup_context.view_paths, ActionView::FallbackFileSystemResolver.new("/")
   end
 
   test "add fallbacks just once in nested fallbacks calls" do
-    @lookup_context.with_fallbacks do
+    assert_deprecated do
       @lookup_context.with_fallbacks do
-        assert_equal 3, @lookup_context.view_paths.size
+        @lookup_context.with_fallbacks do
+          assert_equal 3, @lookup_context.view_paths.size
+        end
       end
     end
+
+    @lookup_context = @lookup_context.with_fallbacks.with_fallbacks
+    assert_equal 3, @lookup_context.view_paths.size
   end
 
   test "generates a new details key for each details hash" do