You have "be to," an English phrase that's one of the devices used to set things in future time [English has no future tense].
The first, "how likely do you think you ARE TO do that part" is the question form of "you ARE [likely] TO do that part." This "ARE TO " specifies a plan or arrangement for the future.
The second, "you ARE not TO do the test...." conveys an order.
[The third use of BE TO sets forth a fate or destiny: "She met Leadbelly, who WAS TO become the greatest folksinger of his time."]
Your seeing TO BE as a syntactic and semantic unit shows that you're already a pretty good English grammarian. [[But you'll never make much money in the trade.]]
Student or Learner