Closes rails/rails#18864: Renaming transactional fixtures to transactional tests

I’m renaming all instances of `use_transcational_fixtures` to
`use_transactional_tests` and “transactional fixtures” to
“transactional tests”.

I’m deprecating `use_transactional_fixtures=`. So anyone who is
explicitly setting this will get a warning telling them to use
`use_transactional_tests=` instead.

I’m maintaining backwards compatibility—both forms will work.
`use_transactional_tests` will check to see if
`use_transactional_fixtures` is set and use that, otherwise it will use
itself. But because `use_transactional_tests` is a class attribute
(created with `class_attribute`) this requires a little bit of hoop
jumping. The writer method that `class_attribute` generates defines a
new reader method that return the value being set. Which means we can’t
set the default of `true` using `use_transactional_tests=` as was done
previously because that won’t take into account anyone using
`use_transactional_fixtures`. Instead I defined the reader method
manually and it checks `use_transactional_fixtures`. If it was set then
it should be used, otherwise it should return the default, which is
`true`. If someone uses `use_transactional_tests=` then it will
overwrite the backwards-compatible method with whatever they set.

1 files changed, 2 insertions, 2 deletions

diff --git a/activerecord/test/cases/transaction_isolation_test.rb b/activerecord/test/cases/transaction_isolation_test.rb
index f89c26532d..2f7d208ed2 100644
--- a/activerecord/test/cases/transaction_isolation_test.rb
+++ b/activerecord/test/cases/transaction_isolation_test.rb
@@ -2,7 +2,7 @@ require 'cases/helper'
 
 unless ActiveRecord::Base.connection.supports_transaction_isolation?
   class TransactionIsolationUnsupportedTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     class Tag < ActiveRecord::Base
     end
@@ -17,7 +17,7 @@ end
 
 if ActiveRecord::Base.connection.supports_transaction_isolation?
   class TransactionIsolationTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
+    self.use_transactional_tests = false
 
     class Tag < ActiveRecord::Base
       self.table_name = 'tags'