I agree that the time unit should be in the variable name. The code itself should do a good job of explaining "what" is happening, but you generally need comments to explain "why" this code exists. Why is the test advancing the time, and why are we advancing the time at this line of the test?
networkTimeMs++; // Callback occurs after timeout
timeSec++; // Advance time to check whether dependent properties update
utcTime++; // Leap second, DON'T advance ntpTime
In a performance language your "real types" aren't somehow more expensive and so you should only use the built-in primitives when they accurately reflect your intent. So I would write:
time += Duration::from_millis(1);
But I would expect that "time unit should be in the variable name" is a reasonable choice in a language which doesn't have this affordance, and I needn't care about performance because apparently the language doesn't either.
I also wonder why we've named this variable "time". Maybe we're a very abstract piece of software and so we know nothing more specific? I would prefer to name it e.g. "timeout" or "flight" or "exam_finishes" if we know why we care about this.
