test(ct): finish tests for UnitLesson model
test(ct): finish tests for UnitLesson model

raccoongang/socraticqs2,raccoongang/socraticqs2,raccoongang/socraticqs2,raccoongang/socraticqs2,cjlee112/socraticqs2,cjlee112/socraticqs2,cjlee112/socraticqs2,cjlee112/socraticqs2