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# frozen_string_literal: true
require "cases/helper"
unless ActiveRecord::Base.connection.supports_transaction_isolation?
class TransactionIsolationUnsupportedTest < ActiveRecord::TestCase
self.use_transactional_tests = false
class Tag < ActiveRecord::Base
end
test "setting the isolation level raises an error" do
assert_raises(ActiveRecord::TransactionIsolationError) do
Tag.transaction(isolation: :serializable) { Tag.connection.materialize_transactions }
end
end
end
else
class TransactionIsolationTest < ActiveRecord::TestCase
self.use_transactional_tests = false
class Tag < ActiveRecord::Base
self.table_name = "tags"
end
class Tag2 < ActiveRecord::Base
self.table_name = "tags"
end
setup do
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.
if ActiveRecord::Base.connection.transaction_isolation_levels.include?(:read_uncommitted)
test "read uncommitted" do
Tag.transaction(isolation: :read_uncommitted) do
assert_equal 0, Tag.count
Tag2.create
assert_equal 1, Tag.count
end
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
if ActiveRecord::Base.connection.transaction_isolation_levels.include?(:repeatable_read)
test "repeatable read" do
tag = Tag.create(name: "jon")
Tag.transaction(isolation: :repeatable_read) do
tag.reload
Tag2.find(tag.id).update(name: "emily")
tag.reload
assert_equal "jon", tag.name
end
tag.reload
assert_equal "emily", tag.name
end
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
end