What is the test for reimbursing a plaintiff's defense costs?

In order to be entitled to equitable reimbursement of defense costs, as requested in Count Two, the insurer must prove: (1) the insurer immediately defended the suit against the insured in its entirety; (2) the insurer paid attorney fees and expenses to defend claims not even potentially covered; and (3) the insurer expressly reserved its right to seek reimbursement for fees and expenses paid to defendant claims not even potentially covered. Buss v. Superior Court, 16 Cal.4th 35, 47-50 (1997).