What is the test for a request for counsel in a criminal case?

"[T]he presumption raised by a[n] [incarcerated] suspect's request for counsel--that he considers himself unable to deal with the pressures of custodial interrogation without legal assistance--does not disappear simply because the police have approached the suspect, still in custody, still without counsel, about a separate investigation." Id. Thus, where a suspect is in an inherently coercive environment such as a jail or a place where his freedom is significantly restricted, the interrogation is in custodial surroundings even though the suspect believes he is speaking to a friend. See, e.g., United States v. Brown, 466 F.2d 493, 459 (10th Cir.1982); United States v. Surridge, 687 F.2d 250, 253 (8th Cir.1982), cert. denied, 459 U.S. 1044, 103 S.Ct. 465, 74 L.Ed.2d 614 (1982).