Possible bug with `test` instruction

[VickyMerzOwn]

Was going through threads-intro/loop.s.
This is what it looks like:

.main
.top
sub  $1,%dx
test $0,%dx     
jgte .top         
halt

If I run: ./x86.py -p loop.s -t 1 -i 100 -R dx -c, I get the following output:

dx          Thread 0         
    0   
   -1   1000 sub  $1,%dx
   -1   1001 test $0,%dx
   -1   1002 jgte .top
   -1   1003 halt

My doubt is the following:
If dx is initialised to 0.
By 1001 test $0, %dx, it becomes -1, and here the constant 0 is greater than -1.
So in 1002 jgte .top should send the process in a loop, shouldn't it?
Or am I missing something?