From 77ca887dd12c25ad398b712af2e9ab41f276d6b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafael=20Fran=C3=A7a?= <rafael@franca.dev>
Date: Sun, 29 Dec 2019 11:07:46 -0300
Subject: [PATCH] Merge pull request #38117 from
 nicolasdular/nicolasdular/fix-frozen-strings-in-to-sentence

Return unfrozen strings from to_sentence
---
 activesupport/CHANGELOG.md                           | 12 ++++++++++++
 .../lib/active_support/core_ext/array/conversions.rb |  8 ++++----
 .../test/core_ext/array/conversions_test.rb          |  7 +++++++
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 1466e369bf..8b63458632 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,15 @@
+*   `Array#to_sentence` no longer returns a frozen string.
+
+    Before:
+        ['one', 'two'].to_sentence.frozen?
+        # => true
+
+    After:
+        ['one', 'two'].to_sentence.frozen?
+        # => false
+
+    *Nicolas Dular*
+
 *   Update `ActiveSupport::Messages::Metadata#fresh?` to work for cookies with expiry set when
     `ActiveSupport.parse_json_times = true`.
 
diff --git a/activesupport/lib/active_support/core_ext/array/conversions.rb b/activesupport/lib/active_support/core_ext/array/conversions.rb
index ea688ed2ea..dee78b3b13 100644
--- a/activesupport/lib/active_support/core_ext/array/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/array/conversions.rb
@@ -74,13 +74,13 @@ def to_sentence(options = {})
 
     case length
     when 0
-      ""
+      +""
     when 1
-      "#{self[0]}"
+      +"#{self[0]}"
     when 2
-      "#{self[0]}#{options[:two_words_connector]}#{self[1]}"
+      +"#{self[0]}#{options[:two_words_connector]}#{self[1]}"
     else
-      "#{self[0...-1].join(options[:words_connector])}#{options[:last_word_connector]}#{self[-1]}"
+      +"#{self[0...-1].join(options[:words_connector])}#{options[:last_word_connector]}#{self[-1]}"
     end
   end
 
diff --git a/activesupport/test/core_ext/array/conversions_test.rb b/activesupport/test/core_ext/array/conversions_test.rb
index 0a7c43d421..914702c1b7 100644
--- a/activesupport/test/core_ext/array/conversions_test.rb
+++ b/activesupport/test/core_ext/array/conversions_test.rb
@@ -68,6 +68,13 @@ def test_always_returns_string
     assert_instance_of String, [ActiveSupport::SafeBuffer.new("one"), "two"].to_sentence
     assert_instance_of String, [ActiveSupport::SafeBuffer.new("one"), "two", "three"].to_sentence
   end
+
+  def test_returns_no_frozen_string
+    assert_not [].to_sentence.frozen?
+    assert_not ["one"].to_sentence.frozen?
+    assert_not ["one", "two"].to_sentence.frozen?
+    assert_not ["one", "two", "three"].to_sentence.frozen?
+  end
 end
 
 class ToSTest < ActiveSupport::TestCase
-- 
GitLab