Test Sequelize#isDefined
Test Sequelize#isDefined

Added tests for the isDefined method.
See http://docs.sequelizejs.com/class/lib/sequelize.js~Sequelize.html#instance-method-isDefined

Signed-off-by: Tobias Kahse <16fa801a7112a0cba48b29d4c9a846fde9dac60c@hpe.com>

BlinkUX/sequelize-mock