test-dirstate: actually test the append code path in dirstate v2

Apparently it's not sufficient to modify a file to force the dirstate
write-out, so the append code path was untested.

By removing a file instead of changing we're forcing append to happen.

tests/test-dirstate.t

@@ -1,207 +1,217 b''
 #testcases dirstate-v1 dirstate-v2
 
 #if dirstate-v2
   $ cat >> $HGRCPATH << EOF
   > [format]
   > use-dirstate-v2=1
   > [storage]
   > dirstate-v2.slow-path=allow
   > EOF
 #endif
 
 ------ Test dirstate._dirs refcounting
 
   $ hg init t
   $ cd t
   $ mkdir -p a/b/c/d
   $ touch a/b/c/d/x
   $ touch a/b/c/d/y
   $ touch a/b/c/d/z
   $ hg ci -Am m
   adding a/b/c/d/x
   adding a/b/c/d/y
   adding a/b/c/d/z
   $ hg mv a z
   moving a/b/c/d/x to z/b/c/d/x
   moving a/b/c/d/y to z/b/c/d/y
   moving a/b/c/d/z to z/b/c/d/z
 
 Test name collisions
 
   $ rm z/b/c/d/x
   $ mkdir z/b/c/d/x
   $ touch z/b/c/d/x/y
   $ hg add z/b/c/d/x/y
   abort: file 'z/b/c/d/x' in dirstate clashes with 'z/b/c/d/x/y'
   [255]
   $ rm -rf z/b/c/d
   $ touch z/b/c/d
   $ hg add z/b/c/d
   abort: directory 'z/b/c/d' already in dirstate
   [255]
 
   $ cd ..
 
 Issue1790: dirstate entry locked into unset if file mtime is set into
 the future
 
 Prepare test repo:
 
   $ hg init u
   $ cd u
   $ echo a > a
   $ hg add
   adding a
   $ hg ci -m1
 
 Set mtime of a into the future:
 
   $ touch -t 203101011200 a
 
 Status must not set a's entry to unset (issue1790):
 
   $ hg status
   $ hg debugstate
   n 644          2 2031-01-01 12:00:00 a
 
 Test modulo storage/comparison of absurd dates:
 
 #if no-aix
   $ touch -t 195001011200 a
   $ hg st
   $ hg debugstate
   n 644          2 2018-01-19 15:14:08 a
 #endif
 
 Verify that exceptions during a dirstate change leave the dirstate
 coherent (issue4353)
 
   $ cat > ../dirstateexception.py <<EOF
   > from __future__ import absolute_import
   > from mercurial import (
   >   error,
   >   extensions,
   >   mergestate as mergestatemod,
   > )
   > 
   > def wraprecordupdates(*args):
   >     raise error.Abort(b"simulated error while recording dirstateupdates")
   > 
   > def reposetup(ui, repo):
   >     extensions.wrapfunction(mergestatemod, 'recordupdates',
   >                             wraprecordupdates)
   > EOF
 
   $ hg rm a
   $ hg commit -m 'rm a'
   $ echo "[extensions]" >> .hg/hgrc
   $ echo "dirstateex=../dirstateexception.py" >> .hg/hgrc
   $ hg up 0
   abort: simulated error while recording dirstateupdates
   [255]
   $ hg log -r . -T '{rev}\n'
   1
   $ hg status
   ? a
 
 #if dirstate-v2
 Check that folders that are prefixes of others do not throw the packer into an
 infinite loop.
 
   $ cd ..
   $ hg init infinite-loop
   $ cd infinite-loop
   $ mkdir hgext3rd hgext
   $ touch hgext3rd/__init__.py hgext/zeroconf.py
   $ hg commit -Aqm0
 
   $ hg st -c
   C hgext/zeroconf.py
   C hgext3rd/__init__.py
 
   $ cd ..
 
 Check that the old dirstate data file is removed correctly and the new one is
 valid.
 
   $ dirstate_data_files () {
   >   find .hg -maxdepth 1 -name "dirstate.*"
   > }
 
   $ find_dirstate_uuid () {
   >   hg debugstate --docket | grep uuid | sed 's/.*uuid: \(.*\)/\1/'
   > }
 
+  $ find_dirstate_data_size () {
+  >   hg debugstate --docket | grep 'size of dirstate data' | sed 's/.*size of dirstate data: \(.*\)/\1/'
+  > }
+
   $ dirstate_uuid_has_not_changed () {
   >   # Non-Rust always rewrites the whole dirstate
   >   if [ $# -eq 1 ] || ([ -n "$HGMODULEPOLICY" ] && [ -z "${HGMODULEPOLICY##*rust*}" ]) || [ -n "$RHG_INSTALLED_AS_HG" ]; then
   >     test $current_uid = $(find_dirstate_uuid)
   >   else
   >     echo "not testing because using Python implementation"
   >   fi
   > }
 
   $ cd ..
   $ hg init append-mostly
   $ cd append-mostly
   $ mkdir dir dir2
   $ touch dir/a dir/b dir/c dir/d dir/e dir2/f
   $ hg commit -Aqm initial
   $ hg st
   $ dirstate_data_files | wc -l
    *1 (re)
   $ current_uid=$(find_dirstate_uuid)
 
 Nothing changes here
 
   $ hg st
   $ dirstate_data_files | wc -l
    *1 (re)
   $ dirstate_uuid_has_not_changed
   not testing because using Python implementation (no-rust no-rhg !)
 
 Trigger an append with a small change
 
-  $ echo "modified" > dir2/f
+  $ current_data_size=$(find_dirstate_data_size)
+  $ rm dir2/f
   $ hg st
-  M dir2/f
+  ! dir2/f
   $ dirstate_data_files | wc -l
    *1 (re)
   $ dirstate_uuid_has_not_changed
   not testing because using Python implementation (no-rust no-rhg !)
+  $ new_data_size=$(find_dirstate_data_size)
+  $ [ "$current_data_size" -eq "$new_data_size" ]; echo $?
+  0 (no-rust no-rhg !)
+  1 (rust !)
+  1 (no-rust rhg !)
 
 Unused bytes counter is non-0 when appending
   $ touch file
   $ hg add file
   $ current_uid=$(find_dirstate_uuid)
 
 Trigger a rust/rhg run which updates the unused bytes value
   $ hg st
-  M dir2/f
   A file
+  ! dir2/f
   $ dirstate_data_files | wc -l
    *1 (re)
   $ dirstate_uuid_has_not_changed
   not testing because using Python implementation (no-rust no-rhg !)
 
   $ hg debugstate --docket | grep unused
   number of unused bytes: 0 (no-rust no-rhg !)
   number of unused bytes: [1-9]\d* (re) (rhg no-rust !)
   number of unused bytes: [1-9]\d* (re) (rust no-rhg !)
   number of unused bytes: [1-9]\d* (re) (rust rhg !)
 
 Delete most of the dirstate to trigger a non-append
   $ hg rm dir/a dir/b dir/c dir/d
   $ dirstate_data_files | wc -l
    *1 (re)
   $ dirstate_uuid_has_not_changed also-if-python
   [1]
 
 Check that unused bytes counter is reset when creating a new docket
 
   $ hg debugstate --docket | grep unused
   number of unused bytes: 0
 
 #endif
 
   $ cd ..