diff --git a/actionpack/test/dispatch/debug_exceptions_test.rb b/actionpack/test/dispatch/debug_exceptions_test.rb
index 8660deb634..24526fb00e 100644
--- a/actionpack/test/dispatch/debug_exceptions_test.rb
+++ b/actionpack/test/dispatch/debug_exceptions_test.rb
@@ -10,6 +10,8 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
       @closed = false
     end
 
+    # We're obliged to implement this (even though it doesn't actually
+    # get called here) to properly comply with the Rack SPEC
     def each
     end