When unit testing Apache Flink with ProcessFunctionTestHarnesses

KeyedOneInputStreamOperatorTestHarness<String, Event, Alert> testHarness = ProcessFunctionTestHarnesses.forKeyedProcessFunction

The testHarness has access to 2 classes to get the number of active timers in the keyed process function.

1. int i = testHarness.getProcessingTimeService().getNumActiveTimers()
2. int k = testHarness.numProcessingTimeTimers()

I’ve looked at the java doc of the both TestProcessingTimeService and InternalTimeServiceManager but the description doesn’t say much.

What is the difference b/w two and which should be used?

In my KeyedProcessFunction, I set and then delete a processing timer. At the end my UT, I expect there to be 0 active processing timers. From the above snippet, k passes the assertion of being equal to 0 but i fails, with it’s actual value being 1.