def run
unless lockfile_path.exist?
raise Error, "Lockfile missing!"
end
previous_resolution = lockfile.load(lockfile_path.read)
spec = specfile.read(previous_resolution.sources)
changes = spec_change_set(spec, previous_resolution)
manifests = changes.same? ? previous_resolution.manifests : changes.analyze
partial_manifests = ManifestSet.deep_strip(manifests, dependency_names)
unpinnable_sources = previous_resolution.sources - partial_manifests.map(&:source)
unpinnable_sources.each(&:unpin!)
resolution = resolver.resolve(spec, partial_manifests)
persist_resolution(resolution)
end