What is the test for establishing a "primary activities" of a criminal street gang?

The phrase "primary activities" means "the commission of one or more of the statutorily enumerated crimes [must be] one of the group's 'chief' or 'principal' occupations. [Citation.] That definition would necessarily exclude the occasional commission of those crimes by the group's members." (People v. Sengpadychith (2001) 26 Cal.4th 316, 323 (Sengpadychith).) This evidence is necessary to differentiate criminal street gangs from other organizations that may occasionally commit enumerated offenses, such as environmental groups, or police departments. (Id. at pp. 323-324.) "Sufficient proof of the gang's primary activities might consist of evidence that the group's members consistently and repeatedly have committed criminal activity listed in the gang statute. Also sufficient might be expert testimony . . . [the gang] . . . was primarily engaged in . . . statutorily enumerated felonies." (Id. at p. 324.)