Conversion of type '{ totalAssets: jest.Mock<any, any, any>; balanceOf: jest.Mock<any, any, any>; assetsBalanceOf: jest.Mock<any, any, any>; calculateDepositFee: jest.Mock<any, any, any>; }' to type 'StBTC' may be a mistake because neither type sufficiently overlaps with the other. If this was intentional, convert the expression to 'unknown' first.