From 32de26447ce4233854f4a1eefae980ce2fa3562e Mon Sep 17 00:00:00 2001
From: Jonas Arvidsson <jonas054@gmail.com>
Date: Sat, 6 Jun 2020 08:28:26 +0200
Subject: [PATCH] [Fix #8108] Disregard whitespace lines in HeredocIndentation

Empty lines were already excluded for calculation of indentation in
Layout/HeredocIndentation. We need to do the same thing for lines
consisting only of whitespace.
---
 CHANGELOG.md                                  |  1 +
 lib/rubocop/cop/layout/heredoc_indentation.rb |  2 +-
 .../cop/layout/heredoc_indentation_spec.rb    | 62 +++++++++++++------
 3 files changed, 44 insertions(+), 21 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 93b077e24c8..73f478c19c2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 * [#8083](https://github.com/rubocop-hq/rubocop/issues/8083): Fix an error for `Lint/MixedRegexpCaptureTypes` cop when using a regular expression that cannot be processed by regexp_parser gem. ([@koic][])
 * [#8081](https://github.com/rubocop-hq/rubocop/issues/8081): Fix a false positive for `Lint/SuppressedException` when empty rescue block in `do` block. ([@koic][])
 * [#8096](https://github.com/rubocop-hq/rubocop/issues/8096): Fix a false positive for `Lint/SuppressedException` when empty rescue block in defs. ([@koic][])
+* [#8108](https://github.com/rubocop-hq/rubocop/issues/8108): Fix infinite loop in `Layout/HeredocIndentation` auto-correct. ([@jonas054][])
 
 ## 0.85.0 (2020-06-01)
 
diff --git a/lib/rubocop/cop/layout/heredoc_indentation.rb b/lib/rubocop/cop/layout/heredoc_indentation.rb
index 6725994457a..e2c617567ac 100644
--- a/lib/rubocop/cop/layout/heredoc_indentation.rb
+++ b/lib/rubocop/cop/layout/heredoc_indentation.rb
@@ -147,7 +147,7 @@ def base_indent_level(node)
         def indent_level(str)
           indentations = str.lines
                             .map { |line| line[/^\s*/] }
-                            .reject { |line| line == "\n" }
+                            .reject { |line| line.end_with?("\n") }
           indentations.empty? ? 0 : indentations.min_by(&:size).size
         end
 
diff --git a/spec/rubocop/cop/layout/heredoc_indentation_spec.rb b/spec/rubocop/cop/layout/heredoc_indentation_spec.rb
index 491ca3fecc2..f0b37939b45 100644
--- a/spec/rubocop/cop/layout/heredoc_indentation_spec.rb
+++ b/spec/rubocop/cop/layout/heredoc_indentation_spec.rb
@@ -189,29 +189,51 @@ def foo
         RUBY
       end
 
-      it 'registers an offense for not indented enough with empty lines' do
-        # rubocop:disable Layout/HeredocIndentation
-        expect_offense(<<-RUBY)
-          def baz
-            <<~#{quote}MSG#{quote}
-            foo
-^^^^^^^^^^^^^^^ Use 2 spaces for indentation in a heredoc.
-
-              bar
-            MSG
-          end
-        RUBY
-        # rubocop:enable Layout/HeredocIndentation
-
-        expect_correction(<<-CORRECTION)
-          def baz
-            <<~#{quote}MSG#{quote}
+      { empty: '', whitespace: '    ' }.each do |description, line|
+        it "registers an offense for not indented enough with #{description} line" do
+          # Using <<- in this section makes the code more readable.
+          # rubocop:disable Layout/HeredocIndentation
+          expect_offense(<<-RUBY)
+            def baz
+              <<~#{quote}MSG#{quote}
               foo
+^^^^^^^^^^^^^^^^^ Use 2 spaces for indentation in a heredoc.
+#{line}
+                bar
+              MSG
+            end
+          RUBY
+
+          expect_correction(<<-CORRECTION)
+            def baz
+              <<~#{quote}MSG#{quote}
+                foo
+#{line}
+                  bar
+              MSG
+            end
+          CORRECTION
+        end
 
+        it "registers an offense for too deep indented with #{description} line" do
+          expect_offense(<<-RUBY)
+            <<~#{quote}RUBY2#{quote}
+                  foo
+^^^^^^^^^^^^^^^^^^^^^ Use 2 spaces for indentation in a heredoc.
+#{line}
                 bar
-            MSG
-          end
-        CORRECTION
+            RUBY2
+          RUBY
+
+          expect_correction(<<-CORRECTION)
+            <<~#{quote}RUBY2#{quote}
+                foo
+#{line}
+              bar
+            RUBY2
+          CORRECTION
+        end
+        # rubocop:enable Layout/HeredocIndentation
       end
 
       it 'displays message to use `<<~` instead of `<<`' do