Missing key should throw KeyError

It should not throw a NameError, but should throw a KeyError.

Fixes #26278

1 files changed, 6 insertions, 0 deletions

diff --git a/actionpack/test/dispatch/header_test.rb b/actionpack/test/dispatch/header_test.rb
index 7a155d70cb..374e618b42 100644
--- a/actionpack/test/dispatch/header_test.rb
+++ b/actionpack/test/dispatch/header_test.rb
@@ -158,4 +158,10 @@ class HeaderTest < ActiveSupport::TestCase
     assert_equal({ "HTTP_REFERER"=>"http://example.com/",
                   "CONTENT_TYPE"=>"text/plain" }, env)
   end
+
+  test "fetch exception" do
+    assert_raises KeyError do
+      @headers.fetch(:some_key_that_doesnt_exist)
+    end
+  end
 end