3 files changed, 33 insertions, 1 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index d186fd2c10..55a3cbfd60 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   Fixed the inferred table name of a HABTM auxiliar table inside a schema.
+
+    Fixes #14824
+
+    *Eric Chahin*
+
 *   Remove unused `:timestamp` type. Transparently alias it to `:datetime`
     in all cases. Fixes inconsistencies when column types are sent outside of
     `ActiveRecord`, such as for XML Serialization.
diff --git a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
index 44486ad758..30b11c01eb 100644
--- a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
+++ b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
@@ -11,7 +11,7 @@ module ActiveRecord::Associations::Builder
         end
 
         def join_table
-          @join_table ||= [@lhs_class.table_name, klass.table_name].sort.join("\0").gsub(/^(.*_)(.+)\0\1(.+)/, '\1\2_\3').gsub("\0", "_")
+          @join_table ||= [@lhs_class.table_name, klass.table_name].sort.join("\0").gsub(/^(.*[._])(.+)\0\1(.+)/, '\1\2_\3').gsub("\0", "_")
         end
 
         private
diff --git a/activerecord/test/cases/adapters/postgresql/schema_test.rb b/activerecord/test/cases/adapters/postgresql/schema_test.rb
index 11ec7599a3..b9e296ed8f 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_test.rb
@@ -50,6 +50,16 @@ class SchemaTest < ActiveRecord::TestCase
     self.table_name = 'things'
   end
 
+  class Song < ActiveRecord::Base
+    self.table_name = "music.songs"
+    has_and_belongs_to_many :albums
+  end
+
+  class Album < ActiveRecord::Base
+    self.table_name = "music.albums"
+    has_and_belongs_to_many :songs
+  end
+
   def setup
     @connection = ActiveRecord::Base.connection
     @connection.execute "CREATE SCHEMA #{SCHEMA_NAME} CREATE TABLE #{TABLE_NAME} (#{COLUMNS.join(',')})"
@@ -109,6 +119,22 @@ class SchemaTest < ActiveRecord::TestCase
     assert !@connection.schema_names.include?("test_schema3")
   end
 
+  def test_habtm_table_name_with_schema
+    ActiveRecord::Base.connection.execute <<-SQL
+      DROP SCHEMA IF EXISTS music CASCADE;
+      CREATE SCHEMA music;
+      CREATE TABLE music.albums (id serial primary key);
+      CREATE TABLE music.songs (id serial primary key);
+      CREATE TABLE music.albums_songs (album_id integer, song_id integer);
+    SQL
+
+    song = Song.create
+    album = Album.create
+    assert_equal song, Song.includes(:albums).references(:albums).first
+  ensure
+    ActiveRecord::Base.connection.execute "DROP SCHEMA music CASCADE;"
+  end
+
   def test_raise_drop_schema_with_nonexisting_schema
     assert_raises(ActiveRecord::StatementInvalid) do
       @connection.drop_schema "test_schema3"