diff --git a/test/support/task_test_case.rb b/test/support/task_test_case.rb
index 2b27f80a9..8c539a90a 100644
--- a/test/support/task_test_case.rb
+++ b/test/support/task_test_case.rb
@@ -4,9 +4,11 @@ class TaskTestCase < ActiveSupport::TestCase
     # This suppresses default stdout and makes Rails.env.test? checks unnecessary.
     @original_stdout = $stdout
     $stdout = File.open(File::NULL, 'w')
+    ActiveSupport::Deprecation.warn('`TaskTestCase` class will be removed soon.' \
+                                    ' Use `capture_io` and `assert_output` instead')
   end
 
   teardown do
     $stdout = @original_stdout
   end
-end
\ No newline at end of file
+end