@Test
void isJarFile() throws IOException {

    Path path = Files.createTempFile("robozonky-", ".jar");
    assumeThat(path).exists();
    File file = path.toFile();
    assertThat(FileUtil.isJarFile(file)).isTrue();
    file.delete();
    assumeThat(FileUtil.isJarFile(file)).isFalse();
}