Extend STF tests for new resource negotiation options

[tobous]

With the recent rework of the wizards to select the resources when creating (#1035) and receiving (#1037) resource negotiations, the possibility of which kind of resources to share and how to represent the shared reference points locally has increased. In particular, any folder can now be chosen as a reference point (when creating and receiving a resource negotiation) and the shared reference point can also be represented by creating a new (non-project) folder (when receiving a resource negotiation).

These new options should be covered by the STF tests.

New options to cover:

• Selecting an existing non-project directory as a reference point to share when creating a resource negotiation.
• Selecting an existing non-project directory as a reference point to use when receiving a resource negotiation.
• Selecting the option to create a new non-project directory to represent the shared reference point when receiving a resource negotiation.

Additionally, it would be nice to test the logic to ensure that no nested reference points are created. The options to cover:

• When creating a resource negotiation:

  • Trying to select a parent resource of an already shared reference point. (Are not displayed if there aren't any shareable child resources.)
  • Trying to select an already shared reference point or one of its child resources. (Are not displayed in tree with current implementation; not sure if testable.)

• When receiving a resource negotiation:

  • Trying to select a parent resource of an already shared reference point.
  • Trying to select an already shared reference point or one of its child resources.
  • Trying to select the same resource for different reference points of the same resource negotiation.
  • Trying to select representations for different reference points of the same resource negotiation that would lead to nested reference points.