Waffle mock contract should revert if value is sent to nonpayable function

[ItsNickBarry]

I am deploying a mock like this:

const mock = await deployMockContract(deployer, [
  'function fn () external view returns (bool)',
]);

Then I am calling fn with value, and testing how the revert is handled, but the mock doesn't revert. I've tried marking the fn function as both view and nonpayable.