Update `titlelize` regex to allow apostrophes

In 4b685aa the regex in `titlelize` was updated to not match
apostrophes to better reflect the nature of the transformation.
Unfortunately this had the side effect of breaking capitalization
on the first word of a sub-string, e.g:

  >> "This was 'fake news'".titleize
  => "This Was 'fake News'"

This is fixed by extending the look-behind to also check for a
word character on the other side of the apostrophe.

Fixes #28312.

3 files changed, 18 insertions, 1 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 58956ad0e8..fb7379d153 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,19 @@
+*   Update `titlelize` regex to allow apostrophes
+
+    In 4b685aa the regex in `titlelize` was updated to not match apostrophes to
+    better reflect the nature of the transformation. Unfortunately this had the
+    side effect of breaking capitalization on the first word of a sub-string, e.g:
+
+        >> "This was 'fake news'".titleize
+        => "This Was 'fake News'"
+
+    This is fixed by extending the look-behind to also check for a word
+    character on the other side of the apostrophe.
+
+    Fixes #28312.
+
+    *Andrew White*
+
 *   Add `rfc3339` aliases to `xmlschema` for `Time` and `ActiveSupport::TimeWithZone`
 
     For naming consistency when using the RFC 3339 profile of ISO 8601 in applications.
diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index 8ccb735c6d..51c221ac0e 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -161,7 +161,7 @@ module ActiveSupport
     #   titleize('TheManWithoutAPast')       # => "The Man Without A Past"
     #   titleize('raiders_of_the_lost_ark')  # => "Raiders Of The Lost Ark"
     def titleize(word)
-      humanize(underscore(word)).gsub(/\b(?<!['’`])[a-z]/) { |match| match.capitalize }
+      humanize(underscore(word)).gsub(/\b(?<!\w['’`])[a-z]/) { |match| match.capitalize }
     end
 
     # Creates the name of a table like Rails does for models to table names.
diff --git a/activesupport/test/inflector_test_cases.rb b/activesupport/test/inflector_test_cases.rb
index b660987d92..f3352e3301 100644
--- a/activesupport/test/inflector_test_cases.rb
+++ b/activesupport/test/inflector_test_cases.rb
@@ -271,6 +271,7 @@ module InflectorTestCases
     "¿por qué?"             => "¿Por Qué?",
     "Fred’s"                => "Fred’s",
     "Fred`s"                => "Fred`s",
+    "this was 'fake news'"  => "This Was 'Fake News'",
     ActiveSupport::SafeBuffer.new("confirmation num") => "Confirmation Num"
   }