isGeneratedDartFile function
Whether path looks like a code-generated Dart file.
Generators follow the convention name.tag.dart (e.g. foo.g.dart,
foo.freezed.dart, foo.mocks.dart, foo.mapper.dart). Hand-written
files are just name.dart.
Implementation
@visibleForTesting
bool isGeneratedDartFile(String path) {
final slash = path.lastIndexOf(RegExp(r'[/\\]'));
final base = slash == -1 ? path : path.substring(slash + 1);
if (!base.endsWith('.dart')) return false;
return '.'.allMatches(base).length >= 2;
}