6886a14f

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Fix diff output to show actual mutated source rather than label text

Each mutation operator now returns a 5th element, srcTransform :: Text -> Text,
that maps the original source span to the replacement source text. recordMutation
uses this to pre-compute mutRecMutatedLine at instrumentation time, so
formatMutationLog can display the correct mutated line in the diff instead of
the human-readable label (e.g. "not e") which was wrong for Negate mutations.

Timeline