It is an unfair labor practice for an employer to:

(1) Interfere with, restrain, or coerce employees in the exercise of their rights guaranteed by this chapter;

(2) Control, dominate, or interfere with a bargaining representative;

(3) Engage in or create the impression of surveillance of activities protected by this chapter;

(4) Discriminate against an employee who has filed an unfair labor practice charge or who has given testimony under this chapter; or

(5) Refuse to engage in collective bargaining.