I have been able to run the FlashDiagnostics on the Sparkfun RedBoard Turbo. A M0 processor with W25Q32BV 32M-Bit Winbond memory chip. I had to modify the variant.h and variant.cpp files as Sparkfun had omitted to include Arduino access for the on board SPImemory.
I have posted details of the edits and a copy of the output obtained on the Sparkfun forum:
https://forum.sparkfun.com/viewtopic.php?f=145&t=49805
Thanks for the library
Ted