Deletes created files, database tables, and reverts all environment changes.
This method needs to be invoked for both unit and integration tests.
Overrides TestBase::tearDown
TestBase::prepareDatabasePrefix()
TestBase::changeDatabasePrefix()
TestBase::prepareEnvironment()
protected function tearDown() {
// The DatabaseExpirableStorage class has a destructor which deletes rows
// from the key_value_expire table. We need to make sure the destructor
// runs before the table is deleted.
$this->container
->set('keyvalue.expirable', NULL);
db_drop_table('key_value_expire');
parent::tearDown();
}