String result = purgeThumbnailJob.execute();

        assertEquals("Deleted 100 thumbnail files.", result);
    }

    // Test execute with custom expiry
    public void test_execute_customExpiry() {
        long customExpiry = 10L * 24 * 60 * 60 * 1000L; // 10 days
        purgeThumbnailJob.expiry(customExpiry);
        thumbnailManager.setPurgeCallCount(5);