Heartbeat test fails when using shorter delay

[gatsinski]

Currently, the heartbeat occurs every second test waits for 6 seconds by sleeping the thread before observing the node's vault and the expected number of transactions is correct. 7 transactions - one for each second passed plus the initial one.

Successful CircleCI build

When I reduce the number of seconds to just 1 (8bf4101), I expected to have 2 transactions but instead, it's only the initial one.

Failed CircleCI build

A developer should be able to test any number of scheduled executions, including the minimal. Is this an issue with the testing approach or with Corda itself?