tests: rework util.debugstacktrace tests

Prepare for adding another test.

tests/test-debugcommands.t

@@ -1,133 +1,140 b''
   $ cat << EOF >> $HGRCPATH
   > [format]
   > usegeneraldelta=yes
   > EOF
 
   $ hg init debugrevlog
   $ cd debugrevlog
   $ echo a > a
   $ hg ci -Am adda
   adding a
   $ hg debugrevlog -m
   format : 1
   flags  : inline, generaldelta
   
   revisions     :  1
       merges    :  0 ( 0.00%)
       normal    :  1 (100.00%)
   revisions     :  1
       full      :  1 (100.00%)
       deltas    :  0 ( 0.00%)
   revision size : 44
       full      : 44 (100.00%)
       deltas    :  0 ( 0.00%)
   
   chunks        :  1
       0x75 (u)  :  1 (100.00%)
   chunks size   : 44
       0x75 (u)  : 44 (100.00%)
   
   avg chain length  : 0
   max chain length  : 0
   compression ratio : 0
   
   uncompressed data size (min/max/avg) : 43 / 43 / 43
   full revision size (min/max/avg)     : 44 / 44 / 44
   delta size (min/max/avg)             : 0 / 0 / 0
 
 Test debugindex, with and without the --debug flag
   $ hg debugindex a
      rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
        0         0       3   ....       0 b789fdd96dc2 000000000000 000000000000 (re)
   $ hg --debug debugindex a
      rev    offset  length  ..... linkrev nodeid                                   p1                                       p2 (re)
        0         0       3   ....       0 b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 (re)
   $ hg debugindex -f 1 a
      rev flag   offset   length     size  .....   link     p1     p2       nodeid (re)
        0 0000        0        3        2   ....      0     -1     -1 b789fdd96dc2 (re)
   $ hg --debug debugindex -f 1 a
      rev flag   offset   length     size  .....   link     p1     p2                                   nodeid (re)
        0 0000        0        3        2   ....      0     -1     -1 b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 (re)
 
 debugdelta chain basic output
 
   $ hg debugdeltachain -m
       rev  chain# chainlen     prev   delta       size    rawsize  chainsize     ratio   lindist extradist extraratio
         0       1        1       -1    base         44         43         44   1.02326        44         0    0.00000
 
   $ hg debugdeltachain -m -T '{rev} {chainid} {chainlen}\n'
   0 1 1
 
   $ hg debugdeltachain -m -Tjson
   [
    {
     "chainid": 1,
     "chainlen": 1,
     "chainratio": 1.02325581395,
     "chainsize": 44,
     "compsize": 44,
     "deltatype": "base",
     "extradist": 0,
     "extraratio": 0.0,
     "lindist": 44,
     "prevrev": -1,
     "rev": 0,
     "uncompsize": 43
    }
   ]
 
 Test max chain len
   $ cat >> $HGRCPATH << EOF
   > [format]
   > maxchainlen=4
   > EOF
 
   $ printf "This test checks if maxchainlen config value is respected also it can serve as basic test for debugrevlog -d <file>.\n" >> a
   $ hg ci -m a
   $ printf "b\n" >> a
   $ hg ci -m a
   $ printf "c\n" >> a
   $ hg ci -m a
   $ printf "d\n" >> a
   $ hg ci -m a
   $ printf "e\n" >> a
   $ hg ci -m a
   $ printf "f\n" >> a
   $ hg ci -m a
   $ printf 'g\n' >> a
   $ hg ci -m a
   $ printf 'h\n' >> a
   $ hg ci -m a
   $ hg debugrevlog -d a
   # rev p1rev p2rev start   end deltastart base   p1   p2 rawsize totalsize compression heads chainlen
       0    -1    -1     0   ???          0    0    0    0     ???      ????           ?     1        0 (glob)
       1     0    -1   ???   ???          0    0    0    0     ???      ????           ?     1        1 (glob)
       2     1    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        2 (glob)
       3     2    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        3 (glob)
       4     3    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        4 (glob)
       5     4    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        0 (glob)
       6     5    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        1 (glob)
       7     6    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        2 (glob)
       8     7    -1   ???   ???        ???  ???  ???    0     ???      ????           ?     1        3 (glob)
   $ cd ..
 
 Test internal debugstacktrace command
 
   $ cat > debugstacktrace.py << EOF
   > from mercurial.util import debugstacktrace, dst, sys
   > def f():
-  >     dst('hello world')
+  >     debugstacktrace(f=sys.stdout)
+  >     g()
   > def g():
-  >     f()
-  >     debugstacktrace(skip=-5, f=sys.stdout)
-  > g()
+  >     dst('hello from g\\n', skip=1)
+  >     h()
+  > def h():
+  >     dst('hi ...\\nfrom h hidden in g', 1)
+  > f()
   > EOF
   $ python debugstacktrace.py
-  hello world at:
-   debugstacktrace.py:7 in * (glob)
-   debugstacktrace.py:5 in g
-   debugstacktrace.py:3 in f
   stacktrace at:
-   debugstacktrace.py:7 *in * (glob)
-   debugstacktrace.py:6 *in g (glob)
-   */util.py:* in debugstacktrace (glob)
+   debugstacktrace.py:10 in * (glob)
+   debugstacktrace.py:3  in f
+  hello from g
+   at:
+   debugstacktrace.py:10 in * (glob)
+   debugstacktrace.py:4  in f
+  hi ...
+  from h hidden in g at:
+   debugstacktrace.py:10 in * (glob)
+   debugstacktrace.py:4  in f
+   debugstacktrace.py:7  in g