require 'cases/helper' class TransactionIsolationUnsupportedTest < ActiveRecord::TestCase self.use_transactional_fixtures = false class Tag < ActiveRecord::Base end setup do if ActiveRecord::Base.connection.supports_transaction_isolation? skip "database supports transaction isolation; test is irrelevant" end end test "setting the isolation level raises an error" do assert_raises(ActiveRecord::TransactionIsolationError) do Tag.transaction(isolation: :serializable) { } end end end class TransactionIsolationTest < ActiveRecord::TestCase self.use_transactional_fixtures = false class Tag < ActiveRecord::Base self.table_name = 'tags' end class Tag2 < ActiveRecord::Base self.table_name = 'tags' end setup do unless ActiveRecord::Base.connection.supports_transaction_isolation? skip "database does not support setting transaction isolation" end Tag.establish_connection 'arunit' Tag2.establish_connection 'arunit' Tag.destroy_all end # It is impossible to properly test read uncommitted. The SQL standard only # specifies what must not happen at a certain level, not what must happen. At # the read uncommitted level, there is nothing that must not happen. test "read uncommitted" do Tag.transaction(isolation: :read_uncommitted) do assert_equal 0, Tag.count Tag2.create assert_equal 1, Tag.count end end # We are testing that a dirty read does not happen test "read committed" do Tag.transaction(isolation: :read_committed) do assert_equal 0, Tag.count Tag2.transaction do Tag2.create assert_equal 0, Tag.count end end assert_equal 1, Tag.count end # We are testing that a nonrepeatable read does not happen test "repeatable read" do tag = Tag.create(name: 'jon') Tag.transaction(isolation: :repeatable_read) do tag.reload Tag2.find(tag.id).update_attributes(name: 'emily') tag.reload assert_equal 'jon', tag.name end tag.reload assert_equal 'emily', tag.name end # We are only testing that there are no errors because it's too hard to # test serializable. Databases behave differently to enforce the serializability # constraint. test "serializable" do Tag.transaction(isolation: :serializable) do Tag.create end end test "setting isolation when joining a transaction raises an error" do Tag.transaction do assert_raises(ActiveRecord::TransactionIsolationError) do Tag.transaction(isolation: :serializable) { } end end end test "setting isolation when starting a nested transaction raises error" do Tag.transaction do assert_raises(ActiveRecord::TransactionIsolationError) do Tag.transaction(requires_new: true, isolation: :serializable) { } end end end end