assertEquals("Deleted 5 thumbnail files.", result);
        assertEquals(customExpiry, thumbnailManager.getPurgeExpiry());
    }

    // Test execute with exception thrown
    public void test_execute_exceptionThrown() {
        thumbnailManager.setThrowException(true);
        thumbnailManager.setExceptionMessage("Purge failed");

        String result = purgeThumbnailJob.execute();