3 files changed, 7 insertions, 1 deletions
diff --git a/actionpack/test/abstract/callbacks_test.rb b/actionpack/test/abstract/callbacks_test.rb
index 9c2261bf76..fdc09bd951 100644
--- a/actionpack/test/abstract/callbacks_test.rb
+++ b/actionpack/test/abstract/callbacks_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "abstract_unit"
 
 module AbstractController
@@ -42,7 +44,7 @@ module AbstractController
       def aroundz
         @aroundz = "FIRST"
         yield
-        @aroundz << "SECOND"
+        @aroundz += "SECOND"
       end
 
       def index
diff --git a/actionpack/test/abstract/collector_test.rb b/actionpack/test/abstract/collector_test.rb
index 1cd3526483..a4770b66e1 100644
--- a/actionpack/test/abstract/collector_test.rb
+++ b/actionpack/test/abstract/collector_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "abstract_unit"
 
 module AbstractController
diff --git a/actionpack/test/abstract/translation_test.rb b/actionpack/test/abstract/translation_test.rb
index 4893144905..7138044c03 100644
--- a/actionpack/test/abstract/translation_test.rb
+++ b/actionpack/test/abstract/translation_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "abstract_unit"
 
 module AbstractController