Absolutely! Pyret's test section has a "satisfies" keyword for property tests. E.g.:

  check:
    insert(a-value, a-balanced-tree) satisfies is-balanced
  end

or even

  check:
    tree-examples = [ ... ]
    values = [ ... ]
    for each2(t in tree-examples, v in values):
      insert(t, v) satisfies is-rbtree
    end
  end