This test does the following with two channels a and b:

• adds a DISCARD layer to a to disccard 50% of down messages
• sends 20 messages to the group, randomly using a and b as senders, and randomly choosing OOB or non-OOB
• wait 10 seconds for 20 messages to be received by each of a and b
• print out the messages received
• remove the DISCARD layer from a
• wait 2.5 seconds for further messages to arrive
• assert that 20 messages have arrived for each channel a and b

The test fails on the assertion, with results such as:

expected 20 elements, but got 19 (list=[1, 4, 3, 8, 6, 7, 10, 13, 15, 20, 2, 5, 9, 12, 14, 16, 17, 18, 19]), missing=[0, 11]