Need to add additional validation in 'join' control and fail execution in case if it is not passed

[Anastasia Kuznetsova]

Steps to reproduce:
1) create workflow for example with 2 regular tasks and 1 task with "join" control :

wf:
task1:
  ...
task2:
 ...
task3:
   join: 10

2) execute created wf

Observed result:
Workflow execution will be in SUCCESS state, because task1 and task2 were successful, but task3 will never be executed.

Expected result:
Workflow execution will fail because of "10" is incorrect and workflow has less then 10 tasks at all.

[Renat Akhmerov (rakhmerov)]

This is definitely a valid ticket. However, I think this is a part of a bigger task (BP) that needs to address post-load validation of workflows such as: integrity (e.g. references to not existing tasks, actions etc.), dead-lock condition analysis and others.

[Renat Akhmerov (rakhmerov)]

We need to discuss it further.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/224714

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/224714
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=17bfd2ad97de5c82e6fa33b549adf8efd0432d81
Submitter: Jenkins
Branch: master

commit 17bfd2ad97de5c82e6fa33b549adf8efd0432d81
Author: Renat Akhmerov <email address hidden>
Date: Thu Sep 17 15:46:02 2015 +0300

    Add semantics validation of direct workflow 'join' tasks

    * E.g. if we have a task marked with 'join: 10' but it has only
      2 inbound tasks then task specification will raise an exception.
    * Minor refactoring and style changes

    Change-Id: I311aadd0afa2e05213da1fdd999233dee03afda3
    Closes-Bug: #1404205