Multiple case conditions

[sti0]

Hey there,
I've got a question about the usage of case conditions:

Scenario:

• 2 tasks, B follows A, but B could be executed without execution A
• 2 parameters to handle the execution of A (exec_a) and B (exec_b)
• If parameter exec_a is True execute task A
• If parameter exec_b is True execute task B
• Task B uses skip_on_upstream_skip = False to execute if exec_a was False

This works if both execution parameter are True or exec_a is False and exec_b is True. But it don't work if it's vice versa. In that case task B will be executed as well.

from prefect import Flow, Parameter, task
from prefect.tasks.control_flow.case import case


@task
def a(a=None):
    if not a:
        raise ValueError("a missing")
    else:
        print(a)


@task(skip_on_upstream_skip=False)
def b(b=None):
    if not b:
        raise ValueError("b missing")
    else:
        print(b)


with Flow("ab_flow") as flow:
    exec_a = Parameter(name="exec_a", default=True)
    exec_b = Parameter(name="exec_b", default=False)

    with case(exec_a, True):
        t_a = a("hello")

    with case(exec_b, True):
        t_b = b(b="world", upstream_tasks=[t_a])


if __name__ == "__main__":
    flow_state = flow.run()

How could I prevent task B from running if exec_b is set to False?