Test cases for asynchronous & state-related operations.

[hcadavid]

The 'container manager' (which will replace v6's Docker Manager) involves asynchronous operations (e.g., launching job pods) and managing statuses based on these operations. This requires a more formal analysis and the development of unit tests based on a kubernetes test-environment. For this PyTest-kind https://pypi.org/project/pytest-kind/ or Kubetest could be explored.