Mock method implementation using Google Mock

Question

I'm mocking Arduino millis method using Google Mock. This method returns number of milliseconds since device starts. I would like to return increased number (in range 0 to Infinity) on every method call.

So far, I'm mocking this function like that:

EXPECT_CALL(*arduino, millis())
  .WillOnce(Return(0))
  .WillOnce(Return(1))
  .WillOnce(Return(2))
  // and so on...

But it's impractical. Is there a better way which works on infinite number of calls?

Answer 1

You can write a custom action that will return incrementing numbers and use it in WillRepeatedly:

ACTION(ReturnIncreasingIntegers) {
    static int n = 0;
    return ++n;
}

EXPECT_CALL(*arduino, millis())
    .WillRepeatedly(ReturnIncreasingIntegers());

But I would advise against that. The less deterministic your test is, the harder it is to understand the behavior of the code under test there.