What does "test Zhang Tongbi" mean in the calligraphy work "The Poems of Shuhanshanzi Pang Jushi" by Huang Tingjian?

Zhang Tong, a pen maker in the Song Dynasty, Gu Shangu's "Bi Shuo": Zhang Tong's writing has sound, so he wrote against it.

Pen and paper craftsmen of all ages invited famous experts to test the new products. Among Huang Shangu's works, "The Seventeen Envoys of the Road to Scenery" is also a trial work.

"Testing Zhang Tong's pen" means writing with Zhang Tong's new pen.