then:
        releasedVersionsFile.text == expectedFileContent
    }

    ReleasedVersion releasedVersion(String version, long date = System.currentTimeMillis()) {
        new ReleasedVersion(version, format.format(new Date(date)))
    }

    ReleasedVersion snapshot(String baseVersion, long date = System.currentTimeMillis()) {
        releasedVersion("${baseVersion}-${format.format(new Date(date))}", date)
    }