[snip]
Here is a partial report for official Debian package of 3.8.0-rc2.
[snip]
libinterp/corefcn/graphics.cc-tst ...................... PASS 18/21 FAIL 3
scripts/gui/uimenu.m ................................... PASS 0/3 FAIL 3
scripts/plot/util/allchild.m ........................... PASS 2/3 FAIL 1
scripts/plot/util/findall.m ............................ PASS 0/1 FAIL 1
scripts/plot/util/graphics_toolkit.m ................... PASS 0/2 FAIL 2
Those 10 failures are due to not having DISPLAY set, so no worry.