@Test(expected = IllegalArgumentException.class)
public void testGenerateTarGzNoDirectory() throws Exception {

    File rootDir = tempFolder.getRoot().getAbsoluteFile();
    File nonExistentDir = new File(rootDir, "temp");
    Utils.generateTarGz(nonExistentDir, null);
    Assert.fail("Expected an IOException as the directory does not exist");
}