Fixes #18492

- Add check for not deleting previously created fixtures, to overcome sti fixtures from multiple files
- Added fixtures and fixtures test to verify the same

- Fixed wrong fixtures duplicating data insertion in same table

activerecord/lib/active_record/fixtures.rb

@@ -521,13 +521,17 @@ module ActiveRecord
           update_all_loaded_fixtures fixtures_map
 
           connection.transaction(:requires_new => true) do
+            deleted_tables = []
             fixture_sets.each do |fs|
               conn = fs.model_class.respond_to?(:connection) ? fs.model_class.connection : connection
               table_rows = fs.table_rows
 
               table_rows.each_key do |table|
+                unless deleted_tables.include? table
                   conn.delete "DELETE FROM #{conn.quote_table_name(table)}", 'Fixture Delete'
                 end
+                deleted_tables << table
+              end
 
               table_rows.each do |fixture_set_name, rows|
                 rows.each do |row|

activerecord/test/cases/fixtures_test.rb

@@ -672,7 +672,8 @@ class FasterFixturesTest < ActiveRecord::TestCase
 end
 
 class FoxyFixturesTest < ActiveRecord::TestCase
-  fixtures :parrots, :parrots_pirates, :pirates, :treasures, :mateys, :ships, :computers, :developers, :"admin/accounts", :"admin/users"
+  fixtures :parrots, :parrots_pirates, :pirates, :treasures, :mateys, :ships, :computers,
+           :developers, :"admin/accounts", :"admin/users", :live_parrots, :dead_parrots
 
   if ActiveRecord::Base.connection.adapter_name == 'PostgreSQL'
     require 'models/uuid_parent'
@@ -812,6 +813,12 @@ class FoxyFixturesTest < ActiveRecord::TestCase
     assert_equal pirates(:blackbeard), parrots(:polly).killer
   end
 
+  def test_supports_sti_with_respective_files
+    assert_kind_of LiveParrot, live_parrots(:dusty)
+    assert_kind_of DeadParrot, dead_parrots(:deadbird)
+    assert_equal pirates(:blackbeard), dead_parrots(:deadbird).killer
+  end
+
   def test_namespaced_models
     assert admin_accounts(:signals37).users.include?(admin_users(:david))
     assert_equal 2, admin_accounts(:signals37).users.size
@@ -834,9 +841,9 @@ class CustomNameForFixtureOrModelTest < ActiveRecord::TestCase
   set_fixture_class :randomly_named_a9         =>
                         ClassNameThatDoesNotFollowCONVENTIONS,
                     :'admin/randomly_named_a9' =>
-                        Admin::ClassNameThatDoesNotFollowCONVENTIONS,
+                        Admin::ClassNameThatDoesNotFollowCONVENTIONS1,
                     'admin/randomly_named_b0'  =>
-                        Admin::ClassNameThatDoesNotFollowCONVENTIONS
+                        Admin::ClassNameThatDoesNotFollowCONVENTIONS2
 
   fixtures :randomly_named_a9, 'admin/randomly_named_a9',
            :'admin/randomly_named_b0'
@@ -847,15 +854,15 @@ class CustomNameForFixtureOrModelTest < ActiveRecord::TestCase
   end
 
   def test_named_accessor_for_randomly_named_namespaced_fixture_and_class
-    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS,
+    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS1,
                    admin_randomly_named_a9(:first_instance)
-    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS,
+    assert_kind_of Admin::ClassNameThatDoesNotFollowCONVENTIONS2,
                    admin_randomly_named_b0(:second_instance)
   end
 
   def test_table_name_is_defined_in_the_model
-    assert_equal 'randomly_named_table', ActiveRecord::FixtureSet::all_loaded_fixtures["admin/randomly_named_a9"].table_name
-    assert_equal 'randomly_named_table', Admin::ClassNameThatDoesNotFollowCONVENTIONS.table_name
+    assert_equal 'randomly_named_table2', ActiveRecord::FixtureSet::all_loaded_fixtures["admin/randomly_named_a9"].table_name
+    assert_equal 'randomly_named_table2', Admin::ClassNameThatDoesNotFollowCONVENTIONS1.table_name
   end
 end
 

activerecord/test/fixtures/dead_parrots.yml

@@ -0,0 +1,5 @@
+deadbird:
+  name: "Dusty DeadBird"
+  treasures: [ruby, sapphire]
+  parrot_sti_class: DeadParrot
+  killer: blackbeard

activerecord/test/fixtures/live_parrots.yml

@@ -0,0 +1,4 @@
+dusty:
+  name: "Dusty Bluebird"
+  treasures: [ruby, sapphire]
+  parrot_sti_class: LiveParrot

activerecord/test/models/admin/randomly_named_c1.rb

@@ -1,3 +1,7 @@
-class Admin::ClassNameThatDoesNotFollowCONVENTIONS < ActiveRecord::Base
-  self.table_name = :randomly_named_table
+class Admin::ClassNameThatDoesNotFollowCONVENTIONS1 < ActiveRecord::Base
+  self.table_name = :randomly_named_table2
+end
+
+class Admin::ClassNameThatDoesNotFollowCONVENTIONS2 < ActiveRecord::Base
+  self.table_name = :randomly_named_table3
 end

activerecord/test/models/randomly_named_c1.rb

@@ -1,3 +1,3 @@
 class ClassNameThatDoesNotFollowCONVENTIONS < ActiveRecord::Base
-  self.table_name = :randomly_named_table
+  self.table_name = :randomly_named_table1
 end

activerecord/test/schema/schema.rb

@@ -623,7 +623,17 @@ ActiveRecord::Schema.define do
     t.string :type
   end
 
-  create_table :randomly_named_table, force: true do |t|
+  create_table :randomly_named_table1, force: true do |t|
+    t.string  :some_attribute
+    t.integer :another_attribute
+  end
+
+  create_table :randomly_named_table2, force: true do |t|
+    t.string  :some_attribute
+    t.integer :another_attribute
+  end
+
+  create_table :randomly_named_table3, force: true do |t|
     t.string  :some_attribute
     t.integer :another_attribute
   end