What is the test for obtaining consent for a warrantless search?

"A warrantless search may be based on the consent of a person, other than the accused, who has control over the area searched. `[T]he defendant may challenge the validity of the consent insofar as the search infringed his own expectations of privacy under the Fourth Amendment.' [Citation.] The `capacity to claim the protection of the Fourth Amendment depends . . . upon whether the person . . . has a legitimate expectation of privacy in the invaded place.' [Citation.]" (People v. Rivera (2007) 41 Cal.4th 304, 308, fn. 1.)