assertTrue(filename.contains(docid));
    }

    // Test getImageFilename with custom settings
    public void test_getImageFilename_customSettings() {
        thumbnailManager.setImageExtention("jpg");
        thumbnailManager.setSplitSize(5);
        thumbnailManager.setSplitHashSize(20);

        String docid = "1234567890abcdef";
        String filename = thumbnailManager.getImageFilename(docid);

    }

    /**
     * Sets the image file extension for thumbnails.
     *
     * @param imageExtention the file extension to set
     */
    public void setImageExtention(final String imageExtention) {
        this.imageExtention = imageExtention;
    }

    /**
     * Sets the split size for directory organization.
     *
     * @param splitSize the split size to set