Consider the following model:

and this code:

runtimeService.createProcessInstanceByKey("key")
.setVariable(VARIABLE_NAME, "1")
.startBeforeActivity("A")
.executeWithVariablesInReturn();

Expected result:

A single instance of B is active. A was never active

Current result:

A single instance of B is active. A has been started and immediately interrupted (history entries are present).

Reasoning:

When the sub process scope is instantiated, the conditional event should trigger immediately and therefore instantiation should abort.

Side note:

The linked commit contains a similar test case of a different situation.