syntax_data: {"ast_node_type":"other","tokens":[{"end":71,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // test to perform that will confirm or refute that match pair.
context_before:         // Choose a match pair from the first candidate, and use it to determine a
context_after:         let (match_place, test) = self.pick_test(candidates);