Auto-correct does not cache

[cabello]

The first time I run bundle exec rubocop is slower than the sub-sequent ones because of the awesome caching feature.

When using the auto-correct flag -a, it seems to never cache and every single run takes on average the same amount of time.

Expected behavior

Caching should also work when auto-correcting files.

Actual behavior

Every run takes consistently the same amount of time.

Steps to reproduce the problem

➤ time bundle exec rubocop -a
Inspecting 269 files
.............................................................................................................................................................................................................................................................................

269 files inspected, no offenses detected
       10.30 real         9.93 user         0.29 sys
➤ time bundle exec rubocop -a
Inspecting 269 files
.............................................................................................................................................................................................................................................................................

269 files inspected, no offenses detected
       10.18 real         9.80 user         0.29 sys
➤ time bundle exec rubocop -a
Inspecting 269 files
.............................................................................................................................................................................................................................................................................

269 files inspected, no offenses detected
       10.16 real         9.77 user         0.31 sys

Compare to:

➤ time bundle exec rubocop
Inspecting 269 files
.............................................................................................................................................................................................................................................................................

269 files inspected, no offenses detected
       10.99 real        10.54 user         0.40 sys
➤ time bundle exec rubocop
Inspecting 269 files
.............................................................................................................................................................................................................................................................................

269 files inspected, no offenses detected
        1.31 real         1.04 user         0.25 sys

RuboCop version

➤ bundle exec rubocop -V
0.49.1 (using Parser 2.4.0.0, running on ruby 2.3.5 x86_64-darwin16)

Is that a reasonable request? Thanks for the awesome project! ❤️

[pocke]

It seems good to me. But we must refactor the code for auto-correction to implement this feature.

First, we should add auto_correct to NON_CHANGING.

diff --git a/lib/rubocop/result_cache.rb b/lib/rubocop/result_cache.rb
index bd5bb85e..01c240ef 100644
--- a/lib/rubocop/result_cache.rb
+++ b/lib/rubocop/result_cache.rb
@@ -7,7 +7,7 @@ require 'etc'
 module RuboCop
   # Provides functionality for caching rubocop runs.
   class ResultCache
-    NON_CHANGING = %i[color format formatters out debug fail_level
+    NON_CHANGING = %i[color format formatters out debug fail_level auto_correct
                       cache fail_fast stdin parallel].freeze
 
     # Remove old files so that the cache doesn't grow too big. When the
diff --git a/lib/rubocop/runner.rb b/lib/rubocop/runner.rb
index fc405261..46506c7c 100644
--- a/lib/rubocop/runner.rb
+++ b/lib/rubocop/runner.rb
@@ -175,8 +175,6 @@ module RuboCop
         # cops related to calculating the Max parameters for Metrics cops. We
         # need to do that processing and can not use caching.
         !@options[:auto_gen_config] &&
-        # Auto-correction needs a full run. It can not use cached results.
-        !@options[:auto_correct] &&
         # We can't cache results from code which is piped in to stdin
         !@options[:stdin]
     end

But it does not work well from we just changing them.
For example

$ cat test.rb
p "a"



$ rubocop 
Inspecting 1 file
C

Offenses:

test.rb:1:3: C: Style/StringLiterals: Prefer single-quoted strings when you don't need string interpolation or special symbols.
p "a"
  ^^^

1 file inspected, 1 offense detected



# It does not execute auto-correction!
$ rubocop -a
Inspecting 1 file
C

Offenses:

test.rb:1:3: C: Style/StringLiterals: Prefer single-quoted strings when you don't need string interpolation or special symbols.
p "a"
  ^^^

1 file inspected, 1 offense detected

[jonas054]

Thanks, @pocke for the initial work on this!