What is the test for corroboration in a search warrant application?

"Corroboration is not limited to a given form but includes within its ambit any facts, sources, and circumstances which reasonably tend to offer independent support for information claimed to be true. In a police investigation the information given by informants, even where the informant's reliability is not complete, can nevertheless be sufficient to establish the requisite probable cause if it is corroborated in essential respects by other facts, sources or circumstances. [Citation.] Not only may the information in a search warrant affidavit which has been supplied by an informant be corroborated by investigation conducted by law enforcement officials [citation], but also this corroboration need only give the officers reasonable grounds to believe that the informant is truthful [citation]." (People v. Levine (1984) 152 Cal.App.3d 1058, 1065.)

"The purpose served by corroboration is 'to establish that the information provided by the informant did not constitute a made-up story, one fabricated out of whole cloth. Corroboration of part of the information provided by the informant [gives] credibility to the remainder of the information.' [Citation.] It is sufficient that an informant's statements are corroborated in a number of key respects, and a piecemeal approach is not required." (People v. Rochen (1988) 203 Cal.App.3d 684, 689.)

As relevant here, the affidavit in support of the 2012 search warrant states as follows: