t/io/defout.t See if PL_defoutgv works
t/io/dup.t See if >& works right
t/io/errno.t See if $! is correctly set
+t/io/errnosig.t Test case for restoration $! when leaving signal handlers
t/io/fflush.t See if auto-flush on fork/exec/system/qx works
t/io/fs.t See if directory manipulations work
t/io/inplace.t See if inplace editing works