Merge pull request rails#51808 from koic/suppress_rubocop_output_when_code_generation

Suppress RuboCop output when there are no offenses in code generation

Author: rafaelfranca

railties/lib/rails/configuration.rb

@@ -135,7 +135,7 @@ def apply_rubocop_autocorrect_after_generate!
         after_generate do |files|
           parsable_files = files.filter { |file| File.exist?(file) && file.end_with?(".rb") }
           unless parsable_files.empty?
-            system(RbConfig.ruby, "bin/rubocop", "-A", "--fail-level=E", *parsable_files, exception: true)
+            system(RbConfig.ruby, "bin/rubocop", "-A", "--fail-level=E", "--format=quiet", *parsable_files, exception: true)
           end
         end
       end

railties/test/application/generators_test.rb

@@ -263,7 +263,7 @@ def check_expected
         end
 
         output = rails("generate", "model", "post", "title:string", "body:string")
-        assert_match(/3 files inspected, no offenses detected/, output)
+        assert_no_match(/3 files inspected, no offenses detected/, output)
       end
 
       test "generators with apply_rubocop_autocorrect_after_generate! and pretend" do