From 714b13d9af4d58fb545cd7d2a8269c759e59f389 Mon Sep 17 00:00:00 2001
From: fatkodima <fatkodima123@gmail.com>
Date: Wed, 22 Jul 2020 18:05:23 +0300
Subject: [PATCH] Support autocorrect for `Lint/Loop` cop

---
 CHANGELOG.md                           |  1 +
 config/default.yml                     |  1 +
 docs/modules/ROOT/pages/cops_lint.adoc |  4 ++--
 lib/rubocop/cop/lint/loop.rb           | 23 ++++++++++++++++++++-
 spec/rubocop/cop/lint/loop_spec.rb     | 28 +++++++++++++++++++++-----
 5 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 120deeb36b9..34ad1fa511a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
 * [#8432](https://github.com/rubocop-hq/rubocop/pull/8432): Add new `Lint/FloatComparison` cop. ([@fatkodima][])
 * [#8376](https://github.com/rubocop-hq/rubocop/pull/8376): Add new `Lint/MissingSuper` cop. ([@fatkodima][])
 * [#8415](https://github.com/rubocop-hq/rubocop/pull/8415): Add new `Style/ExplicitBlockArgument` cop. ([@fatkodima][])
+* [#8383](https://github.com/rubocop-hq/rubocop/pull/8383): Support autocorrect for `Lint/Loop` cop. ([@fatkodima][])
 * [#8339](https://github.com/rubocop-hq/rubocop/pull/8339): Add `Config#for_badge` as an efficient way to get a cop's config merged with its department's. ([@marcandre][])
 * [#5067](https://github.com/rubocop-hq/rubocop/issues/5067): Add new `Style/StringConcatenation` cop. ([@fatkodima][])
 * [#7425](https://github.com/rubocop-hq/rubocop/pull/7425): Add new `Lint/TopLevelReturnWithArgument` cop. ([@iamravitejag][])
diff --git a/config/default.yml b/config/default.yml
index 10d1abc5640..32de0b76987 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -1559,6 +1559,7 @@ Lint/Loop:
   StyleGuide: '#loop-with-break'
   Enabled: true
   VersionAdded: '0.9'
+  VersionChanged: '0.89'
 
 Lint/MissingCopEnableDirective:
   Description: 'Checks for a `# rubocop:enable` after `# rubocop:disable`.'
diff --git a/docs/modules/ROOT/pages/cops_lint.adoc b/docs/modules/ROOT/pages/cops_lint.adoc
index 48e6d40e41e..8ae0fa273cb 100644
--- a/docs/modules/ROOT/pages/cops_lint.adoc
+++ b/docs/modules/ROOT/pages/cops_lint.adoc
@@ -1711,9 +1711,9 @@ This cop checks for interpolated literals.
 
 | Enabled
 | Yes
-| No
+| Yes
 | 0.9
-| -
+| 0.89
 |===
 
 This cop checks for uses of `begin...end while/until something`.
diff --git a/lib/rubocop/cop/lint/loop.rb b/lib/rubocop/cop/lint/loop.rb
index 63674b67f34..b0cb38278a3 100644
--- a/lib/rubocop/cop/lint/loop.rb
+++ b/lib/rubocop/cop/lint/loop.rb
@@ -43,6 +43,8 @@ module Lint
       #     break if some_condition
       #   end
       class Loop < Base
+        extend AutoCorrector
+
         MSG = 'Use `Kernel#loop` with `break` rather than ' \
               '`begin/end/until`(or `while`).'
 
@@ -57,7 +59,26 @@ def on_until_post(node)
         private
 
         def register_offense(node)
-          add_offense(node.loc.keyword)
+          body = node.body
+
+          add_offense(node.loc.keyword) do |corrector|
+            corrector.replace(body.loc.begin, 'loop do')
+            corrector.remove(keyword_and_condition_range(node))
+            corrector.insert_before(body.loc.end, build_break_line(node))
+          end
+        end
+
+        def keyword_and_condition_range(node)
+          node.body.loc.end.end.join(node.source_range.end)
+        end
+
+        def build_break_line(node)
+          conditional_keyword = node.while_post_type? ? 'unless' : 'if'
+          "break #{conditional_keyword} #{node.condition.source}\n#{indent(node)}"
+        end
+
+        def indent(node)
+          ' ' * node.loc.column
         end
       end
     end
diff --git a/spec/rubocop/cop/lint/loop_spec.rb b/spec/rubocop/cop/lint/loop_spec.rb
index 4333f563131..dc37b668bf8 100644
--- a/spec/rubocop/cop/lint/loop_spec.rb
+++ b/spec/rubocop/cop/lint/loop_spec.rb
@@ -3,17 +3,35 @@
 RSpec.describe RuboCop::Cop::Lint::Loop do
   subject(:cop) { described_class.new }
 
-  it 'registers an offense for begin/end/while' do
+  it 'registers an offense and corrects for begin/end/while' do
     expect_offense(<<~RUBY)
-      begin something; top; end while test
-                                ^^^^^ Use `Kernel#loop` with `break` rather than `begin/end/until`(or `while`).
+      begin
+        something
+      end while test
+          ^^^^^ Use `Kernel#loop` with `break` rather than `begin/end/until`(or `while`).
+    RUBY
+
+    expect_correction(<<~RUBY)
+      loop do
+        something
+      break unless test
+      end
     RUBY
   end
 
   it 'registers an offense for begin/end/until' do
     expect_offense(<<~RUBY)
-      begin something; top; end until test
-                                ^^^^^ Use `Kernel#loop` with `break` rather than `begin/end/until`(or `while`).
+      begin
+        something
+      end until test
+          ^^^^^ Use `Kernel#loop` with `break` rather than `begin/end/until`(or `while`).
+    RUBY
+
+    expect_correction(<<~RUBY)
+      loop do
+        something
+      break if test
+      end
     RUBY
   end