An example of a ParDo with Timers that hangs when running under TestStream.
When running gradle test -d you will see the following:
17:02:29.631 [DEBUG] [TestEventLogger] com.andrewjones.beam.TimerTest > testTimer STANDARD_OUT
17:02:29.631 [DEBUG] [TestEventLogger] KV{hello, 100}
17:02:29.662 [DEBUG] [TestEventLogger] KV{hello, 200}
Then the test hangs. Changing:
.addElements(KV.of("hello", 100))
.addElements(KV.of("hello", 200))
To:
.addElements(KV.of("hello", 100), KV.of("hello", 200))
Seems to work. Changing one of the keys will also work.