resolve method

Future<List<CascadingImpact>> resolve({ required String packageName, required String targetVersion, required PubspecData currentPubspec, })

Check for cascading impacts of upgrading packageName to targetVersion.

Process:

1. Fetch the target version's pubspec from pub.dev.
2. Collect its declared dependencies and their version constraints.
3. Compare each constraint against the version currently resolved in the project's lockfile / pubspec.
4. Report any dependency whose current resolved version does not satisfy the target's constraint as a CascadingImpact.

Implementation

Future<List<CascadingImpact>> resolve({
  required String packageName,
  required String targetVersion,
  required PubspecData currentPubspec,
}) async {
  final impacts = <CascadingImpact>[];

  try {
    // Fetch the pubspec of the version we want to upgrade to.
    final targetPubspec = await _pubApi.getVersionPubspec(
      packageName,
      targetVersion,
    );

    if (targetPubspec == null) {
      Logger.warn(
        'CascadeResolver: could not fetch pubspec for '
        '$packageName@$targetVersion',
      );
      return impacts;
    }

    final targetDeps =
        targetPubspec['dependencies'] as Map<String, dynamic>? ?? {};

    for (final entry in targetDeps.entries) {
      final depName = entry.key;
      final constraint = _extractConstraint(entry.value);
      if (constraint == null) continue;

      // Look up the dependency in the current project.
      final currentDep = currentPubspec.dependencies[depName] ??
          currentPubspec.devDependencies[depName];

      // If the project does not use this dependency at all it will be
      // pulled in transitively — no conflict.
      if (currentDep == null || currentDep.resolvedVersion == null) continue;

      final currentVersion = currentDep.resolvedVersion!;

      // Check if the currently resolved version satisfies the target's
      // constraint.
      if (!_versionResolver.satisfies(currentVersion, constraint)) {
        impacts.add(CascadingImpact(
          dependencyName: depName,
          requiredBy: '$packageName@$targetVersion',
          currentConstraint: currentVersion,
          conflictReason:
              'Requires $depName $constraint but current version '
              'is $currentVersion',
        ));
      }
    }
  } catch (e, st) {
    Logger.warn(
      'Failed to resolve cascading impacts for $packageName: $e',
    );
    Logger.debug('Stack trace: $st');
  }

  if (impacts.isNotEmpty) {
    Logger.info(
      'CascadeResolver: found ${impacts.length} cascading impact(s) '
      'for $packageName@$targetVersion',
    );
  }

  return impacts;
}