When a defendant who had opened the door to a barber's shop has been arrested for possession of marijuana, what is the test for placing a person under arrest?

When the defendant who had opened the door sought to close it, the officers quite properly placed her under arrest and entered the premises. They seized the marijuana and certain other dangerous drugs found therein. When a person is actually observed in the commission of a felony, i.e., the act of possessing marijuana, it is self-evident that there exists 'such a state of facts as would lead a man of ordinary care and prudence to believe and conscientiously entertain an honest and strong suspicion that the person is guilty of a crime.' (People v. Ingle, 53 Cal.2d 407, 412, 2 Cal.Rptr. 14, 17, 348 P.2d 577, 580.)