I have a file on my Mac called testdisk.lzh. I believe I downloaded it from a site that was specific to Decmates and CP/M. I was able to refind the site by Googling for "decmate and testdisk.lzh". This may be a copy of the disk you want. I can't say for sure. Downloaded an archiver to my Mac and this lzh file creates a .td0 file which is Teledisk format. I don't have that, but you likely do. Would be interesting to know if this file is the test disk I have or something else. Let me know. Thanks.
Tim Radde