Add conditional logic evaluation to the flow engine

[tomtitherington]

Background & Context*

The flow engine needs to evaluate the conditions defined within a TransitionSchema before the transition can be executed.

Goal*

• When flows are executed any conditions defined within a transition will be evaluated
• When processing auto transitions, if a chosen transition's condition evaluates to Flase then it should choose another. This process should continue until either a transition can be executed or no transition conditions evaluate to True and the flow should be stopped in its current state.

Implementation Details*

Depending on what templating engine we decide on for defining properties within JSON conditions. These properties will need to be injected before the condition is evaluated.

Acceptance Criteria*

• What are the specific, measurable outcomes that indicate the task is completed? Try use a task list of bullet points.

• A simple test asserting that if a condition evaluates to false and no other transition can be taken, the flow will be stopped.

• A simple test with two transitions, both of type automatic where one condition should evaluate to False and the other True. Only the transition that evaluates to True should be executed.

• A simple test with one transition with a condition that evaluates to True. Assert that the transition was in fact executed.

Dependencies

Blockers:

• Setup flow engine #22
• Define conditional transitions using JSON #64

*required field.