does java Files.delete remove files without write permission?

Question

I am trying to write a unit test to test IOException handling in some code. I thought I would be able to create an IOException by removing permissions from a file and trying to delete it. But it looks like the file gets deleted anyway. 1st question is that the expected behavior? If so it seems like a big security hole to me. Second question is anyone have a suggestion on how to create an IOException on either of the two methods Files.delete() or commons.io FileUtils.deleteDirectory(). Following is the unit test code, I have tried both Files.delete on a file and FileUtils.deleteDirectory on a directory. In the latter case I get a fileNotFound exception. The second assertion always fails. Using a debugger I stopped the code and made sure the permissions on unwriteable were 000. I am running java 11 on Redhat 7.

   public void testIOException() throws IOException {
        binPath.toFile().mkdirs();
        Path unwriteablePath =  Paths.get(binPath.toString(), "unwriteable");
        Path writeablePath = Paths.get(binPath.toString(),"writeable");
        File unwriteable = unwriteablePath.toFile();
        unwriteable.createNewFile();
        File writeable = unwriteablePath.toFile();
        writeable.createNewFile();
        Assertions.assertTrue(unwriteable.exists());
        Assertions.assertTrue(writeable.exists());
        Set<PosixFilePermission> perms =
                Files.readAttributes( unwriteablePath, PosixFileAttributes.class).permissions();
        //make file unwriteable
        perms.remove(PosixFilePermission.OWNER_WRITE);
        perms.remove(PosixFilePermission.GROUP_WRITE);
        perms.remove(PosixFilePermission.OTHERS_WRITE);
        perms.remove(PosixFilePermission.OWNER_READ);
        perms.remove(PosixFilePermission.GROUP_READ);
        perms.remove(PosixFilePermission.OTHERS_READ);
        Files.setPosixFilePermissions(unwriteablePath, perms);
        Assertions.assertFalse(unwriteable.canWrite());
       // Deleter deleter = new Deleter(mockConfig);
       // deleter.run();
        try {
            Files.delete(Paths.get(unwriteable.getAbsolutePath()));
        } catch (IOException e) {
            System.out.println("Got expected exception");
        }
        Assertions.assertFalse(writeable.exists());
        Assertions.assertTrue(unwriteable.exists());
    }
}