findSpanByName method
Returns the most recently exported span with the given
name, or null if none match. Most-recent makes per-test
reads stable when a span name happens to be reused across tests.
Implementation
Span? findSpanByName(String name) {
for (var i = _spans.length - 1; i >= 0; i--) {
if (_spans[i].name == name) return _spans[i];
}
return null;
}