What is the test for ineffective assistance of counsel?

"'Reviewing courts defer to counsel's reasonable tactical decisions in examining a claim of ineffective assistance of counsel [citation], and there is a "strong presumption that counsel's conduct falls within the wide range of reasonable professional assistance." [Citation.] . . . . "'Reviewing courts will reverse convictions [on direct appeal] on the ground of inadequate counsel only if the record on appeal affirmatively discloses that counsel had no rational tactical purpose for [his or her] act or omission.'" [Citation.]' [Citation.] If the record on appeal '"'sheds no light on why counsel acted or failed to act in the manner challenged[,] . . . unless counsel was asked for an explanation and failed to provide one, or unless there simply could be no satisfactory explanation,' the claim on appeal must be rejected,"' and the 'claim of ineffective assistance in such a case is more appropriately decided in a habeas corpus proceeding.'" (People v. Vines (2011) 51 Cal.4th 830, 876.) Thus, in "the usual case, where counsel's trial tactics or strategic reasons for challenged decisions do not appear on the record, we will not find ineffective assistance of counsel . . . unless there could be no conceivable reason for counsel's acts or omissions." (People v. Weaver (2001) 26 Cal.4th 876, 926.)

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