Write about delivering change data capture events in a test context.

[renatoliveira]

As observed from an actual test, the Test.getEventBus().deliver() call seems to touch an event queue, so it is necessary to call it multiple times to test both insert and update operations on the same test context.

msg id: https://discordapp.com/channels/246568944213819393/348054624256786434/735517688402804808