Future _checkForMissingChangeError()

in script/tool/lib/src/version_check_command.dart [523:603]
67 lines of code
18 McCabe index (conditional complexity)

  Future<String?> _checkForMissingChangeError(RepositoryPackage package) async {
    // Find the relative path to the current package, as it would appear at the
    // beginning of a path reported by getChangedFiles() (which always uses
    // Posix paths).
    final Directory gitRoot =
        packagesDir.fileSystem.directory((await gitDir).path);
    final String relativePackagePath =
        getRelativePosixPath(package.directory, from: gitRoot) + '/';
    bool hasChanges = false;
    bool needsVersionChange = false;
    bool hasChangelogChange = false;
    for (final String path in _changedFiles) {
      // Only consider files within the package.
      if (!path.startsWith(relativePackagePath)) {
        continue;
      }
      hasChanges = true;

      final List<String> components = p.posix.split(path);
      final bool isChangelog = components.last == 'CHANGELOG.md';
      if (isChangelog) {
        hasChangelogChange = true;
      }

      if (!needsVersionChange &&
          !isChangelog &&
          // The example's main.dart is shown on pub.dev, but for anything else
          // in the example publishing has no purpose.
          !(components.contains('example') && components.last != 'main.dart') &&
          // Changes to tests don't need to be published.
          !components.contains('test') &&
          !components.contains('androidTest') &&
          !components.contains('RunnerTests') &&
          !components.contains('RunnerUITests') &&
          // Ignoring lints doesn't affect clients.
          !components.contains('lint-baseline.xml')) {
        needsVersionChange = true;
      }
    }

    if (!hasChanges) {
      return null;
    }

    if (needsVersionChange) {
      if (_getChangeDescription().split('\n').any((String line) =>
          line.startsWith(_missingVersionChangeJustificationMarker))) {
        logWarning('Ignoring lack of version change due to '
            '"$_missingVersionChangeJustificationMarker" in the '
            'change description.');
      } else {
        printError(
            'No version change found, but the change to this package could '
            'not be verified to be exempt from version changes according to '
            'repository policy. If this is a false positive, please '
            'add a line starting with\n'
            '$_missingVersionChangeJustificationMarker\n'
            'to your PR description with an explanation of why it is exempt.');
        return 'Missing version change';
      }
    }

    if (!hasChangelogChange) {
      if (_getChangeDescription().split('\n').any((String line) =>
          line.startsWith(_missingChangelogChangeJustificationMarker))) {
        logWarning('Ignoring lack of CHANGELOG update due to '
            '"$_missingChangelogChangeJustificationMarker" in the '
            'change description.');
      } else {
        printError(
            'No CHANGELOG change found. If this PR needs an exemption from'
            'the standard policy of listing all changes in the CHANGELOG, '
            'please add a line starting with\n'
            '$_missingChangelogChangeJustificationMarker\n'
            'to your PR description with an explanation of why.');
        return 'Missing CHANGELOG change';
      }
    }

    return null;
  }