What is the test for de facto arrest under the Fourth Amendment?

"'When [a] detention exceeds the boundaries of a permissible investigative stop, the detention becomes a de facto arrest requiring probable cause.' [Citations.]" (People v. Gorrostieta (1993) 19 Cal.App.4th 71, 83.) "[O]nce you search someone for contraband, based on probable cause etc., you have effectively 'arrested' them for purposes of the Fourth Amendment. There are no magic words necessary. Normally, if the strong suspicion of illegal activity proves unfounded, the individual is released. The subject of arrest does not arise. That person was, however, for the brief period of the search, 'arrested' in the eyes of the law. That is the nature of the term de facto-'in fact, indeed, actually.' (Black's Law Dict. (4th ed. 1951) p. 479.)" (Id. at p. 84.)