Metadata constructor Null safety

Implementation

factory Metadata(
    {PlatformSelector? testOn,
    Timeout? timeout,
    bool? skip,
    bool? verboseTrace,
    bool? chainStackTraces,
    int? retry,
    String? skipReason,
    Iterable<String>? tags,
    Map<PlatformSelector, Metadata>? onPlatform,
    Map<BooleanSelector, Metadata>? forTag,
    String? languageVersionComment}) {
  // Returns metadata without forTag resolved at all.
  Metadata unresolved() => Metadata._(
      testOn: testOn,
      timeout: timeout,
      skip: skip,
      verboseTrace: verboseTrace,
      chainStackTraces: chainStackTraces,
      retry: retry,
      skipReason: skipReason,
      tags: tags,
      onPlatform: onPlatform,
      forTag: forTag,
      languageVersionComment: languageVersionComment);

  // If there's no tag-specific metadata, or if none of it applies, just
  // return the metadata as-is.
  if (forTag == null || tags == null) return unresolved();
  tags = Set.from(tags);
  forTag = Map.from(forTag);

  // Otherwise, resolve the tag-specific components. Doing this eagerly means
  // we only have to resolve suite- or group-level tags once, rather than
  // doing it for every test individually.
  var empty = Metadata._();
  var merged = forTag.keys.toList().fold(empty, (Metadata merged, selector) {
    if (!selector.evaluate(tags!.contains)) return merged;
    return merged.merge(forTag!.remove(selector)!);
  });

  if (merged == empty) return unresolved();
  return merged.merge(unresolved());
}